Washington - The Capitol Visitor Center is preparing to open its doors to millions of tourists who now must endure long lines without food, restrooms or shelter to catch a glimpse of the halls of Congress.

The underground center is the largest single construction project in the Capitol's two-century history in terms of size and expense. It opens to the public on Dec. 2.

The final cost of the project is put at $621 million, more than double the estimated cost had the center been completed on schedule three years ago.

With the Capitol Visitor Center, located below ground between the Capitol and the Supreme Court, visits will begin in the vast Emancipation Hall filled with statues moved from the Capitol and a model of the Statue of Freedom that is perched above the Rotunda.

Before beginning tours of the Capitol itself, people can stroll through an exhibition hall with historic documents, artifacts and interactive computers, see shows in two theaters and eat at a 530-seat restaurant area. There are two gift shops and 26 public restrooms.