Art went private at the beginning of the 20th century. Back then Cubism's quest for a new visual language, abstract art's pursuit of purity of form, and Surrealism's sense of inwardness had little appeal to a public who viewed Modern Art as self-serving and difficult.

Ironically then, Modernism's avant-garde concerns led a retreat from the public arena.

It was not always so. If public art is art produced for, and often paid for by, the community, then history encompasses far more public than private art.

The art of ancient Greece and Rome was emphatically public, as were the frescoes and sculptural set pieces of the churches of Renaissance and Baroque Italy, even if their patrons were often private individuals.

Throughout much of the 18th and 19th centuries, public art was synonymous with the kind of stultified municipal sculptures now beloved by pigeons: stiff memorial statues or personifications of civic pride usually loaded with heavy-handed allegorical symbolism.

It was from these artistic doldrums that in the first two decades of the last century artists such as Rodin, Brancusi and Gabo sought to rescue sculpture. In so doing, though, they finally ruptured the traditional relationship between art and public places, taking sculpture off its urban pedestal and into a patron's private space -- or the controlled environment of an art gallery -- and putting it on an equal footing with painting.

At the same time architects such as Frank Lloyd Wright in America and Le Corbusier in Europe were designing Modernist buildings -- stripped of ornamentation, sculptural or otherwise, geometrically cool and conspicuously anonymous. By the middle of the century, however, many of these buildings were to feature large, pristine, abstract sculptures vying for attention out front.

By the early 1970s many artists were looking for new ways to bring art back into the public realm: "Land art" was one such direction. The American artist Christo's "Running Fence" in 1975 -- parachute material mounted on poles and stretched across nearly 10 km of Californian landscape -- involved the approval and cooperation of the entire ranching community and the state's Office of Environmental Protection.

Museums, too, increasingly began to reflect a more public-minded ethos: 1977's factory-style Pompidou Centre in Paris designed by architects Renzo Piano from Italy and Britain's Richard Rodgers is famed for its huge courtyard and "inside-out" design, with its piping, air ducts and the like, all multicolored and outside the structure. Either loved or hated, it has been a huge success and was truly a trailblazer designed as a kind of supermarket for culture.

Perhaps most important, though, were government initiatives in the United States (and later throughout Europe), particularly the Art in Public Places and Percent for Art programs. Both of these encouraged a renewed relationship between art and public space -- the former by assisting local communities to fund, commission and acquire works of public art; the latter by requiring some of the construction budget (usually 1 percent) of buildings over a certain size to be set aside for artworks.

However, the success or failure of public art projects also crucially depends on the authorities' willingness to involve the public in whose living environment the new work will be located. This is particularly true when there are sensitive issues at stake.

Perhaps the most well known example is Maya Lin's minimalist Vietnam Veterans Memorial in Washington, D.C. -- essentially a large horizontal black monolith, inscribed with the names of the dead. It was deemed "unheroic" when it was unveiled in 1982, and a more conventional, figurative sculpture was later added nearby as a sort of compromise.

In other cases, such as Richard Serra's famous "Tilted Arc," which was installed in New York City in 1981, artwork can be seen as an imposition rather than a contribution.

This massive sculpture, which cost the government $175,000, bisected the city's Federal Plaza in Manhattan with 40 meters of steel. The heated public debate that ensued ended nine years later with the court-ordered removal of the piece. Argued a defiant Serra, "I don't think it is the function of art to be pleasing. Art is not democratic."

In contrast, the installation of Daniel Buren's 1986 work "De Plateau" -- a field of truncated columns in the neoclassical courtyard of the Palais Royal in Paris -- was initially blocked by court injunction while a cultural battle raged as to its suitability for the site. Ultimately it was enjoyed by the public simply as a congenial meeting place, and the French artist has gone on to contribute works both to i-Land in Tokyo's Shinjuku (1995) and to the Tokyo Waterfront Redevelopment District (1996).

In my own hometown of Brighton, Bruce Williams's "Kiss Wall," installed on the seafront in 1992, is a serious work with a lighter side, embodying the "kiss-me-quick" jokeyness of seaside culture; it has become a popular photo-opportunity for tourists.

Over the last 20 years or so public art has become more diverse, and especially in Europe and the United States (though South Korea, too, has a statutory Percent for Art provision) more community input has been encouraged. Methods of funding have also become more diffuse, with public money and private investment increasingly working in tandem.

In Britain, 2000 was designated Year of the Artist, an attempt to demonstrate the huge diversity of public settings in which artists work. Ten regional Arts Boards were responsible for planning and managing the project in conjunction with other public- and private-sector bodies. Under its auspices, artists created work in theaters, schools, prisons, airports, care homes, car parks and shopping centres in a range of forms including photography, drama, poetry, music and performance -- as well as the more traditional painting and sculpture.

In its scope and approach, this designated year in Britain clearly illustrates how the emphasis in public art now seems to be on partnership between the artist and the particular community with which he/she is working. Ultimately this is the tightrope an artist operating in the public domain has to walk. Good art should provoke us to ask questions, but too much provocation can cause offense and possibly a violent reaction.

Conversely, art that too easily conforms to the public's preconceptions about what is appropriate can simply become bland decoration and sink without trace into the cacophony of homogenized imagery which already clutters our towns and cities.