Putting the City in Motion.(Brief Article)

Aristotle wrote that men come together in cities to live, but stay in them to live the good life. In Europe that worked brilliantly for the first 2,500 years or so. It was the Greeks who invented the idea of the city, and urbanity continues as a thriving tradition: with 80 percent of its people living in cities, Europe remains the most urbanized continent on earth. Since Aristotle, the metropolitan Greek, Italian or Gaul has been strolling from her house to the agora, piazza or grande place, stop-ping for a spot of shopping, a conversation in a cafe, the latest opera or art exhibition.

But in the first decade of the 21st century, urban life is changing. Cities are less frequently where people stay to lead the good life, and more often way stations for people in pursuit of it. "Cities are now junctions in the flows of people, information, finance and freight," says Nigel Harris, a professor of development planning. "They're less and less places where people live and work." The coming enlargement of the European Union will give residents of up to 13 new member nations freedom of movement within its borders. At the same time, an additional 13.5 million immigrants a year will be needed in the EU just to keep a stable ratio between workers and pensioners over the next half century. All this mobility will make Europe's cities nodes of nomadism, linked to each other by high-speed trains and cheap airline flights. Urban designers, with a freshly pricked interest in transience rather than stasis, are even now dreaming up city-scapes that focus on flows of people and fungible uses for buildings.

The bustle around airports and train stations will make the crowds in Europe's great piazzas look thin by comparison. New city networks will spring up, following transport lines, not old national ties. In the 1990s the Eurostar brought Lon-don closer to Paris than it was to Liverpool. By 2010, routes like the PBKAL (Paris, Brussels, Cologne/Frankfurt, Amsterdam, London) line will have redesigned the map of Europe even further. Meanwhile, urban sprawl is stretching daily commutes: whereas the average European traveled 17 kilometers a day in 1970 to get to and from work, he traveled 35 kilometers a day in 1998. During the late 1990s, flush dot-comers grew used to flying from London to Paris for the day. If trade-liberalization trends continue, it won't just be global elites who country-hop for work. In a phenomenon Harris has called "extreme commuting," cities like London could be flying in planeloads of, say, Moroccans or Turks in weekly rotations to clean streets or hospitals.

In the 20th century, business travelers often avoided the hotel near the railway station, so often associated with grimy red-light districts and cheap pensions. But with so much traveling going on, railway stations and airports will become strong civic hubs, attracting shops, offices and restaurants. Notes Harris: "Once you've got an international transportation terminal, these city areas become international centers, with all kinds of activities, most often based on knowledge industries."

Other public spaces are due for a revamp as well. Earlier architects conceived of train stations as single ...