The growth of cities is probably the most significant global development of the past 100 years - as their number and size has increased, so has their economic, political and cultural power.
The bare figures for the growth are staggering. There were 238 million people living in urban areas in 1900, about 14 per cent of the total world population. Just 100 years later there were 3.2 billion of us in cities and the United Nations Commission on Population estimates that half the world's population will be city dwellers by 2007. In the west, cities are dominant, with about 90 per cent of British people living in urban areas.
The recent creation of an International Council of Museums (ICOM) committee dedicated to city museums reflects the growing global importance of urban life.
Delegates from 13 countries met at the Moscow City Museum in April 2005 to take the first steps to get the international committee for the Collections and Activities of Museums of the City (CAMOC) up and running, although the idea had been bubbling under for some time.
'The time is right to establish an ICOM international committee on museums of cities, not least because of the dominant role the city plays in the cultural and political life of the planet,' says Irina Smagina, the deputy director of the Moscow City Museum, who works alongside the Galina Vedernikova, the director of the museum and the chairwoman of CAMOC.
'Cities matter more than ever and we hope CAMOC will reflect new roles for museums of cities in the 21st century.'
But one of the problems with a grouping of city museums is that there is no clear agreement about what a city museum is. The creation of the new city museum committee was opposed by some members of another ICOM international group, the International Committee for Museums and Collections of Archaeology and History (ICMAH).
This organisation, which is 50 years old and has almost 600 members, already has a working group on city museums. To add to the
confusion, the more informal International Association of City Museums (IACM) has existed since it was formed by 150 delegates at a symposium of city museums held at the Museum of London in 1993.
One of the reasons for opposition to a new international committee for city museums was a belief that there were already enough ways to exchange ideas and information. Supporters felt that the existing organisations were not active enough and not sufficiently interested in museums that look at how cities will develop in the future.
'ICMAH is concerned with history and archaeology, which is too narrow a remit for city museums,' Smagina says. 'We will aim to support and encourage museums in collecting, preserving and presenting original material about the past, present and future of the city, reinforcing the city's identity and contributing to its development. It is a challenge to impress on ICOM that city museums are unique, but we believe it can be done.'
Any problems about the overlapping roles of the three city museum bodies are likely to be tackled at the fourth IACM conference, which is being held from 3-5 November at the Amsterdams Historisch Museum (Amsterdam Historical Museum) in the Netherlands. ICMAH's working group on city museums is one of the organisers and a number of CAMOC members will also attend.
One of the issues they will have to deal with is that city museums are such a varied bunch. They range from the numerous eclectic museums with small collections through to those that specialise in a part of a city's history, such as the Manchester Jewish Museum or the People's Story in Edinburgh.
And then there are the large museums of global cities such as the Museum of London, the Museum of the City of New York and the Edo-Tokyo Museum.
Despite the differences in the range of city museums, what many have in common is the wide variety of material in their collections.
'In contrast to many other types of museums, such as art museums and natural history museums, the special characteristic of a city museum is that it is multi-faceted,' says Renee Kistemaker, a senior consultant at the Amsterdam Historical Museum and the coordinator of ICMAH's city museum working group.
'City museums have collections of cultural, historical and documentary importance, and they have art, archaeology, and sometimes ethnography and even natural history collections.'
City museums also have oral testimonies, paintings, film, video, new media and many other materials that can be used to tell the story of a city. The challenge is to effectively combine and present such diverse collections.
Another area that unites many city museums is contemporary collecting. For many working in the field, this is a vital part of their work.
'If a museum of the city is not contemporary, it has limited its audience primarily to those in search of nostalgia and not history,' says Robert Macdonald, the director emeritus of the Museum of the City of New York. 'The principal mission of a museum of the city is to help its audiences understand why the city they know is the way it is.
'The city developed over time and is understandable only in a historic context,' Macdonald continues. 'But collecting to advance this mission is challenging, particularly in acquiring materials of the most recent history. Museums cannot save everything. What is important? What needs to be saved?'
These questions are related to another challenge that city museums face: how to choose what stories to tell about something as large, complex and diverse as the modern city.
'Telling the story of a city is essentially narrating the stories of urban citizens collectively and individually through time,' Macdonald says. 'Striking a balance between "the grand and the mundane" is essential in making urban history understandable and is of benefit to the communities the museums serve.
Not every voice can be heard in a museum's galleries. The challenge is to select those voices and stories that will help strengthen a sense of time and place and ultimately self for the museum's multi-layered audiences.'
City museums not only have to choose how to balance the grand narrative of a city with individuals' stories, they also have to decide which stories to tell from the vast array of ethnic, social and religious groups that live in most modern cities.
The Museum of London has many choices to make, with about a third of the capital's 7.1 million residents coming from an ethnic minority, according to the 2001 census.
'It is important to look at ethnicity, gender and sexuality not as bolt-ons but as mainstream issues,' says Darryl McIntyre, the group director of public programmes at the Museum of London. 'But you can't be everything to everyone. You need to be strategic.'
The way the Museum of London often works is to form partnerships with other organisations. An example is the London Museums Hub, which is based at the Museum of London, and is working with four partners (Hackney Museum, Redbridge Museum, the Ragged School Museum and Croydon Museum Service) on a project to explore the heritage of refugee groups.
Similarly, the Moscow City Museum has developed a network of linked museums to better cover the city's history, which comprises of the Moscow Museum of Archaeology, the Museum of Christ the Saviour Cathedral, the Old English Court, the Museum of Russian Country-Estate Culture and the Museum of the Russian Accordion.
As well as telling the stories of the past and present of cities, a more tricky area is to look at how they will develop in the future. One way museums can do this is by acting as a forum for debate on how a city should move forward. The Pavillon de l'Arsenal, an architecture centre opened in 1988 by the City of Paris, is often cited as a good role model.
'The Pavillon de l'Arsenal aims to broaden public understanding of the evolution of Paris, explaining the architecture and texture of the city and how it has developed over the years, its condition today and its prospects for the future,' says Ian Jones, the secretary of CAMOC and a partner at Chadwick Jones Associates, a multi-disciplinary partnership that has worked on a number of museum projects.
'The Arsenal essentially deals with urbanism and architecture, not people, except in so far as their lives are shaped by the built environment. Yet it is a forum for explanation and debate and it has helped Parisians to get a better understanding of their city and contribute actively to its development.
'In an ideal world, every city would have a reference point about itself, an Arsenal that would deal with people as well as places, and with the present and future as well as the past,' Jones says.
There are certainly many difficult problems faced by cities that museums can address. Museums in London, Moscow and New York have all been tackling the aftermath of recent terrorist attacks.
Although the Museum of the City of New York has done some collecting related to the destruction of the World Trade Center, the major exhibition on the subject is at the New York State Museum in Albany. The Moscow City Museum also has an exhibition on international terrorism following the events at Nord-Ost and Beslan.
And the Museum of London has been collecting material on the 7 July attacks on the capital. These might be included in a wider display about the long history of terrorism in London as part of the museum's £18m Capital City project, which will complete the story of London up to the present day.
Terrorism is just one of many challenges that cities around the world face; crime, climate change, and demographic change are among the others. And as well as being forums to debate these topics, some city museums also try to provide solutions.
The positive role museums can play in the future of cities, by fostering a sense of community spirit and encouraging regeneration, is extensively covered in The New Town Square, a book by Robert Archibald, the head of the Missouri Historical Society.
As for the future of museums of cities, there are a number of projects that could provide interesting pointers to how they will develop. In the UK, as well as the Museum of London's plans, National Museums Liverpool is to spend £65m creating a new museum to replace the Museum of Liverpool Life. Planned for completion in 2009-10, it will aim to 'look at Britain and the world through the eyes of Liverpool'.
Ian Jones has been working on plans for a museum about Cardiff, although the project was put on hold after the Welsh capital failed in its bid to be the European Capital of Culture in 2008. There is also a £10m scheme to open a Museum of Bristol by 2009.
In the US, the Museum of the City of New York has $50m plans to renovate its building while the San Francisco Museum and Historical Society is to restore the Old Mint building to create a $60m city museum. There is also an $89m scheme to create a museum and cultural centre about Boston.
Elsewhere, the new Capital Museum will open in Beijing in October. The $94m project will cover 60,000 sq metres and will replace the existing Capital Museum, which opened in 1981.
These museum projects reflect the growing importance of cities. The United Nations Commission on Population estimates that 5 billion people - 61 per cent of the world's population - will live in urban areas by 2030.
The challenge for museums is to put aside past differences and work together to develop better ways of helping visitors understand the places where more and more of us are living.
The bare figures for the growth are staggering. There were 238 million people living in urban areas in 1900, about 14 per cent of the total world population. Just 100 years later there were 3.2 billion of us in cities and the United Nations Commission on Population estimates that half the world's population will be city dwellers by 2007. In the west, cities are dominant, with about 90 per cent of British people living in urban areas.
The recent creation of an International Council of Museums (ICOM) committee dedicated to city museums reflects the growing global importance of urban life.
Delegates from 13 countries met at the Moscow City Museum in April 2005 to take the first steps to get the international committee for the Collections and Activities of Museums of the City (CAMOC) up and running, although the idea had been bubbling under for some time.
'The time is right to establish an ICOM international committee on museums of cities, not least because of the dominant role the city plays in the cultural and political life of the planet,' says Irina Smagina, the deputy director of the Moscow City Museum, who works alongside the Galina Vedernikova, the director of the museum and the chairwoman of CAMOC.
'Cities matter more than ever and we hope CAMOC will reflect new roles for museums of cities in the 21st century.'
But one of the problems with a grouping of city museums is that there is no clear agreement about what a city museum is. The creation of the new city museum committee was opposed by some members of another ICOM international group, the International Committee for Museums and Collections of Archaeology and History (ICMAH).
This organisation, which is 50 years old and has almost 600 members, already has a working group on city museums. To add to the
confusion, the more informal International Association of City Museums (IACM) has existed since it was formed by 150 delegates at a symposium of city museums held at the Museum of London in 1993.
One of the reasons for opposition to a new international committee for city museums was a belief that there were already enough ways to exchange ideas and information. Supporters felt that the existing organisations were not active enough and not sufficiently interested in museums that look at how cities will develop in the future.
'ICMAH is concerned with history and archaeology, which is too narrow a remit for city museums,' Smagina says. 'We will aim to support and encourage museums in collecting, preserving and presenting original material about the past, present and future of the city, reinforcing the city's identity and contributing to its development. It is a challenge to impress on ICOM that city museums are unique, but we believe it can be done.'
Any problems about the overlapping roles of the three city museum bodies are likely to be tackled at the fourth IACM conference, which is being held from 3-5 November at the Amsterdams Historisch Museum (Amsterdam Historical Museum) in the Netherlands. ICMAH's working group on city museums is one of the organisers and a number of CAMOC members will also attend.
One of the issues they will have to deal with is that city museums are such a varied bunch. They range from the numerous eclectic museums with small collections through to those that specialise in a part of a city's history, such as the Manchester Jewish Museum or the People's Story in Edinburgh.
And then there are the large museums of global cities such as the Museum of London, the Museum of the City of New York and the Edo-Tokyo Museum.
Despite the differences in the range of city museums, what many have in common is the wide variety of material in their collections.
'In contrast to many other types of museums, such as art museums and natural history museums, the special characteristic of a city museum is that it is multi-faceted,' says Renee Kistemaker, a senior consultant at the Amsterdam Historical Museum and the coordinator of ICMAH's city museum working group.
'City museums have collections of cultural, historical and documentary importance, and they have art, archaeology, and sometimes ethnography and even natural history collections.'
City museums also have oral testimonies, paintings, film, video, new media and many other materials that can be used to tell the story of a city. The challenge is to effectively combine and present such diverse collections.
Another area that unites many city museums is contemporary collecting. For many working in the field, this is a vital part of their work.
'If a museum of the city is not contemporary, it has limited its audience primarily to those in search of nostalgia and not history,' says Robert Macdonald, the director emeritus of the Museum of the City of New York. 'The principal mission of a museum of the city is to help its audiences understand why the city they know is the way it is.
'The city developed over time and is understandable only in a historic context,' Macdonald continues. 'But collecting to advance this mission is challenging, particularly in acquiring materials of the most recent history. Museums cannot save everything. What is important? What needs to be saved?'
These questions are related to another challenge that city museums face: how to choose what stories to tell about something as large, complex and diverse as the modern city.
'Telling the story of a city is essentially narrating the stories of urban citizens collectively and individually through time,' Macdonald says. 'Striking a balance between "the grand and the mundane" is essential in making urban history understandable and is of benefit to the communities the museums serve.
Not every voice can be heard in a museum's galleries. The challenge is to select those voices and stories that will help strengthen a sense of time and place and ultimately self for the museum's multi-layered audiences.'
City museums not only have to choose how to balance the grand narrative of a city with individuals' stories, they also have to decide which stories to tell from the vast array of ethnic, social and religious groups that live in most modern cities.
The Museum of London has many choices to make, with about a third of the capital's 7.1 million residents coming from an ethnic minority, according to the 2001 census.
'It is important to look at ethnicity, gender and sexuality not as bolt-ons but as mainstream issues,' says Darryl McIntyre, the group director of public programmes at the Museum of London. 'But you can't be everything to everyone. You need to be strategic.'
The way the Museum of London often works is to form partnerships with other organisations. An example is the London Museums Hub, which is based at the Museum of London, and is working with four partners (Hackney Museum, Redbridge Museum, the Ragged School Museum and Croydon Museum Service) on a project to explore the heritage of refugee groups.
Similarly, the Moscow City Museum has developed a network of linked museums to better cover the city's history, which comprises of the Moscow Museum of Archaeology, the Museum of Christ the Saviour Cathedral, the Old English Court, the Museum of Russian Country-Estate Culture and the Museum of the Russian Accordion.
As well as telling the stories of the past and present of cities, a more tricky area is to look at how they will develop in the future. One way museums can do this is by acting as a forum for debate on how a city should move forward. The Pavillon de l'Arsenal, an architecture centre opened in 1988 by the City of Paris, is often cited as a good role model.
'The Pavillon de l'Arsenal aims to broaden public understanding of the evolution of Paris, explaining the architecture and texture of the city and how it has developed over the years, its condition today and its prospects for the future,' says Ian Jones, the secretary of CAMOC and a partner at Chadwick Jones Associates, a multi-disciplinary partnership that has worked on a number of museum projects.
'The Arsenal essentially deals with urbanism and architecture, not people, except in so far as their lives are shaped by the built environment. Yet it is a forum for explanation and debate and it has helped Parisians to get a better understanding of their city and contribute actively to its development.
'In an ideal world, every city would have a reference point about itself, an Arsenal that would deal with people as well as places, and with the present and future as well as the past,' Jones says.
There are certainly many difficult problems faced by cities that museums can address. Museums in London, Moscow and New York have all been tackling the aftermath of recent terrorist attacks.
Although the Museum of the City of New York has done some collecting related to the destruction of the World Trade Center, the major exhibition on the subject is at the New York State Museum in Albany. The Moscow City Museum also has an exhibition on international terrorism following the events at Nord-Ost and Beslan.
And the Museum of London has been collecting material on the 7 July attacks on the capital. These might be included in a wider display about the long history of terrorism in London as part of the museum's £18m Capital City project, which will complete the story of London up to the present day.
Terrorism is just one of many challenges that cities around the world face; crime, climate change, and demographic change are among the others. And as well as being forums to debate these topics, some city museums also try to provide solutions.
The positive role museums can play in the future of cities, by fostering a sense of community spirit and encouraging regeneration, is extensively covered in The New Town Square, a book by Robert Archibald, the head of the Missouri Historical Society.
As for the future of museums of cities, there are a number of projects that could provide interesting pointers to how they will develop. In the UK, as well as the Museum of London's plans, National Museums Liverpool is to spend £65m creating a new museum to replace the Museum of Liverpool Life. Planned for completion in 2009-10, it will aim to 'look at Britain and the world through the eyes of Liverpool'.
Ian Jones has been working on plans for a museum about Cardiff, although the project was put on hold after the Welsh capital failed in its bid to be the European Capital of Culture in 2008. There is also a £10m scheme to open a Museum of Bristol by 2009.
In the US, the Museum of the City of New York has $50m plans to renovate its building while the San Francisco Museum and Historical Society is to restore the Old Mint building to create a $60m city museum. There is also an $89m scheme to create a museum and cultural centre about Boston.
Elsewhere, the new Capital Museum will open in Beijing in October. The $94m project will cover 60,000 sq metres and will replace the existing Capital Museum, which opened in 1981.
These museum projects reflect the growing importance of cities. The United Nations Commission on Population estimates that 5 billion people - 61 per cent of the world's population - will live in urban areas by 2030.
The challenge for museums is to put aside past differences and work together to develop better ways of helping visitors understand the places where more and more of us are living.