WASHINGTON — The hand of Freedom rests gently on the hilt of her sword. Her hair falls in long ringlets from beneath her eagle's head helmet. And her face bears a look of perpetual amazement.

Indeed, the 19-foot statue at the center of the new Capitol Visitor Center is surrounded by things of wonder: giant twin skylights, precious artifacts from U.S. history and posh wood-paneled theaters.

In a preview Monday, government officials showed off the $621 million facility in all its polished bronze and marble grandeur. The 580,000-square-foot complex, dug three levels underground beside the east front of the Capitol, opens next month.

The center is the largest single addition to the Capitol in its 215-year history and the biggest since completion of the dome in the 1860s.

The complex was designed as a place where visitors can assemble, out of the weather, for tours of the Capitol or experience the exhibitions and other amenities without taking a Capitol tour. It features a 530-seat restaurant, two orientation theaters and two gift shops. There also are 26 restrooms.

No tickets are required for entrance to the center. Free tickets, which can be obtained in person, online or over the phone, are required for the theaters and tours of the Capitol, which will begin in the center.

Officials said the center can be accessed on foot, by subway or by bus. The main entrance is at First and East Capitol street, across from the Supreme Court.

The center is expected to more than double the number of visitors to the Capitol each year to about 3 million, officials said Monday, making it one of the most visited buildings in the world.

The center has been controversial because of its cost — boosted mainly by security concerns and congressional add-ons — and delays. Many security worries stemmed from the Sept. 11, 2001, terrorist attacks and from a 1998 incident in which a deranged man burst into the Capitol with a revolver and killed two Capitol Police officers.

Government officials said Monday that the project was complex and was being built for the ages.

"Generations of Americans will greatly benefit from all it has to offer," said the acting architect of the Capitol, Stephen Ayers, who helped guide construction for the past 21 months. "The visitor center is a treasure in itself."

In addition to the 1856 statue of Freedom, the model for the one on the Capitol dome, there are 23 other statues from Congress' statuary collection, including of King Kamehameha the Great, scattered throughout the complex.

The Freedom statue, which had been in the basement rotunda of the Russell Senate Office Building since 1993, was disassembled there and reassembled in Emancipation Hall, the center's main gathering place, over the past few months.

The center's polished maroon-and-white marble floors shone Monday under the hall's 18 chandeliers and two 30-by-70-foot skylights, through which the blue sky and the Capitol dome could be seen.

Nearby was the dimly lit exhibition hall where some famous — and seldom-seen — artifacts of U.S. history were on display.

The most haunting is the black-shrouded pine catafalque, or platform, on which once lay the body of Abraham Lincoln and the bodies of other famous Americans, including President Gerald Ford after his death in 2006. It sits behind a sliding bronze grate, said center spokeswoman Sharon Gang, because it will probably be used again.

There are other objects: President John Quincy Adams' metal-tipped ivory walking stick. The tiny ceremonial trowel George Washington used to set the Capitol cornerstone in 1793. The crude penciled radar plot that traced the Japanese attack on Pearl Harbor in 1941.

There are images of some of American history's great figures: the titanic congressional foes, South Carolina's John Calhoun and Massachusetts's Daniel Webster.

And there are famous words: Franklin D. Roosevelt's typed "Day of Infamy" speech, in which he noted "always will we remember the character of the onslaught against us." George Washington's signed letter to Congress reporting the British defeat at Yorktown, ending the Revolutionary War: "I have the Honor to inform Congress, that a Reduction of the British Army under the Command of Lord Cornwallis, is most happily effected."

The exhibition hall also features banks of interactive touch screen displays and an 11-foot cutaway model of the Capitol dome.

"I want to be watching the first person come through the door ... to see that look on their face," said Terrie Rouse, the center's chief of visitor services. "That's what I'm waiting for."