HRADEK NAD NISOU, Czech Republic - For more than 60 years, this remote stretch of bottomland was one of the most closely guarded sectors of Central Europe.

The borders of three countries - Germany, Poland and the Czech Republic - intersect here along the Neisse River. For as long as anyone can remember, the rhythms of life on all sides have been regulated by a dense network of security depots, road barriers and immigration checkpoints that were originally designed to keep people out and prevent others from leaving.

Today, however, the crossings will finally go dark as borders are thrown open here and along frontiers that had separated Eastern and Western Europe since the end of World War II. The last vestiges of the Iron Curtain will disappear.

With fireworks and speeches, the switch began shortly after midnight last night at multiple crossing points up and down the long frontier, as people crossed from country to country freely, no questions asked. At the frontier between Austria and Slovakia, the two nations' leaders ceremonially hand-sawed through a barrier.

For the first time, travelers will be free to drive east from the Algarve coast of Portugal all the way to the edge of Russia without encountering a border guard demanding proof of identification.

"It will be a monumental event," said Martin Puta, mayor of Hradek nad Nisou, a town of about 7,500. "It will not only mean the end of border controls, but also the end of a psychological barrier."

Europe's border-free zone has been expanding gradually since 1985, when Germany, France, the Netherlands, Belgium and Luxembourg agreed to allow one another's citizens free passage into and out of their territories.

The catalyst for the latest extension was the 2004 admission of 10 countries, mostly from Eastern Europe, to the European Union. Preparations have been under way ever since to dismantle the checkpoints and to standardize policing and immigration rules for the new members.

Not all European countries have signed up for borderless travel. Britain and Ireland decided not to join, and most Balkan countries have been kept out. Switzerland, Liechtenstein, Romania, Bulgaria and Cyprus will be phased in over the next four years.

The ease of travel between Eastern and Western Europe had already eased significantly in recent years. Czechs, Poles and Germans in this area, known as the Little Triangle, had to flash only a driver's license when crossing the border. Pedestrians walking over the many international footbridges and paths here could do so without breaking stride.

Merchants advertising cut-rate fuel, cigarettes and liquor, have become a border staple. It's hard to find a gas station these days in Zittau, Germany; residents can save the equivalent of about 80 cents a gallon by driving a half-mile to Porajow, Poland.

Others, however, fret that the new freedoms will bring problems. In particular, many Germans worry that criminals from their less prosperous neighbors will see the open borders as an invitation to come steal cars and rob houses.

Some German police officials have criticized politicians for rushing to eliminate the border controls. Konrad Freiberg, director of Germany's national police union, said German police lack digital radios to communicate with their better-equipped Czech and Polish counterparts. He said there is confusion among officers over how much leeway they have to chase crooks into other countries.

But many residents of the tri-border area here say the increased convenience will outweigh any risks.

In Bogatynia, a town of about 20,000 that serves as the Polish anchor of the Little Triangle, deputy mayor Jerzy Stachyra echoed the sentiment that the concept of borders will take longer to disappear in people's minds. "If you had told me 20 years ago that you could one day cross the border like nothing was there," he said, "I would never have believed it."