It's five to midnight on Buenos Aires's hopping Corrientes Street, and the Il Gatto Pizzeria has run out of highchairs.
"Sorry, sir," says a contrite maitre d' to a newly arrived father holding his wide-awake babe in his arms. "We have a pretty good supply, but they're all occupied." A look around at the highchairs sprinkled throughout the overflowing dining room confirms the report.
Welcome to Buenos Aires, where even the children learn early on that this - forget New York, forget Madrid, forget even Barcelona - is a city that lives at night.
One of the world's great metropolises, mixing the energy of New York with the elegance (though sometimes a bit ragged) of Paris, Buenos Aires puts a Latin spin on the same kind of great migration from the Old to the New Worlds that molded the United States.
Travelers should be sure to stroll through the city's beautiful old neighborhoods and walk down Avenida 9 de Julio - reputed to be the world's widest street - and take in a tango show.
But a visit is not complete without at least one night on the town.
Unlike many other nocturnal cities, Buenos Aires is not just for young people prowling the discos. Here groups of elderly Portea women - arm in arm and strolling the central streets, where theater, movies, and cabarets abound - are just about as visible as the under-25 set.
"My sister lives in Hamburg, and every time she visits, she takes home as a souvenir the 'night life' section of the newspaper that gives all the movies and plays and tango shows that are on to the wee hours," says one spry matron merrily sharing a pizza with three septuagenarian friends a little past midnight. "She says her friends are always amazed."
Amazed, and maybe a little intimidated. For while the people of Buenos Aires are willing to fight for their night life (recent attempts by the city to close many places at 3 a.m. were met with street protests), some foreign tourists are put off by the rigorous Buenos Aires nights.
"In a recent survey we found that more foreign tourists identified tango with our city than any other single factor," says Mnica Kapusta, information director at the City of Buenos Aires's Tourism Department.
"But when we asked what the same tourists did here, only 10 percent had been to a tango show. The common complaint," she adds, "is that they are just too late at night."
The domestic-foreign culture clash is on display at the Cafe Homero tango club in the city's Palermo neighborhood. A show advertised as starting at 11:30 p.m. begins about 12:15 p.m. Explains doorman Sebastian Roldn, "Well, you do have to allow a little leeway for people who are out to dinner and forget the time." The show ends at 2:30 a.m., the crowd cheering for more.
Until recently, Porteos (what the people of Buenos Aires call themselves) never worried much what tourists thought of their late hours.
But with the economy suffering and tourism becoming a bigger income source, the city is taking notice of foreign visitors. (Argentina's economic slump has put a dent in prices in what a few years ago ranked as one of the world's most expensive cities. A good meal of superb Argentine beef can be found readily for $15, but a cup of coffee can be pricey.)
"Traditionally, tourism has not been seen as an important economic activity, but that is changing," says Ms. Kapusta. In a tourism "plan of action" unveiled last year, the city set as a goal a 34 percent increase in visitors by the end of the millennium.
One idea is to get clubs to put on special "early bird" shows. (A recent visitor saw a spectacular tango show starting at 10 p.m.) But mostly the city plans to do a better job promoting what it already has to show off.
Buenos Aires was built on the agricultural riches of the vast Pampa region and the industry of immigrants attracted to share in the wealth. The greatest number came from Italy, but there was also a social and economic connection to Britain. By the 1930s, Argentina was one of the world's richest countries. Buenos Aires became the sophisticated hub of that wealth.
Today the British influence has waned - the state of Harrod's department store on the city's smart pedestrian shopping street, Calle Florida, testifies to the decline. But the elegance and varied old-world architecture of the Recoleta and Retiro neighborhoods are reminders of an opulent past.
The famed Teatro Coln on Avenida 9 de Julio, one of the world's great opera houses, is another testament to that mix of grand past and cosmopolitan present. The Coln has seats for every budget, plus tours for those more into architecture than music.
To get a feel for what gave rise to Buenos Aires, visitors should take in Puerto Madero, the city's old port near the juncture of the Riachuelo River and the Rio de la Plata estuary on which the city sits. Old sailing ships open to the public are moored opposite a long row of brick port buildings now mostly renovated into shops and restaurants.
Beyond the port and fronting the Rio de la Plata is Costanera Sur Wildlife Refuge, which in spite of the polluted waters that surround it, remains a welcome urban nature refuge.
Yet while the Recoleta and Puerto Madero areas are pricey and sophisticated, nothing compares to the more typical neighborhood of San Telmo. Something like New York's Little Italy or Boston's North End, San Telmo makes a stay in Buenos Aires over a Sunday afternoon a must. That's when the neighborhood's many antique shops are joined by a street fair of artisans and old trinkets - including vintage photos of Eva Pern for Evita buffs - all offering up the dusty memorabilia of a great city's past.
San Telmo also offers a hint at why some tourists may not spend more time at the many tango clubs. On Sundays, handsome couples offer shows right on the street. While a night at a club can cost $40 per person, the street show is given for whatever the observer feels moved to drop into the dancer's hat. Still, it can't quite match an evening spent with Argentines caught up in the mood of traditional tango song and dance.