Native Americans from across the country are arriving in the nation's capital to celebrate today's opening of the National Museum of the American Indian.

As workers completed preparations for the noontime dedication ceremony, tribal leaders caught their first glimpses of the sweeping, honey-colored museum near the foot of the sloping incline that leads to the U.S. Capitol.

"Just gorgeous; we're loving it," said Dwain Camp, 67, of the Oklahoma-based Ponca tribe, as he photographed another member of the Ponca, Camela Pappan, who sat near a fountain outside the museum.

After 15 years of preparation, the museum's opening on the Mall is laden with soaring historic significance for Native Americans, who have long struggled for national recognition. As many as 20,000 of them plan to attend the dedication, with many assembling this morning in front of the Smithsonian Castle for a dramatic procession to begin at 9:30 a.m. and move along the Mall to the ceremony at Third Street NW.

Sen. Ben Nighthorse Campbell (R-Colo.), who sponsored legislation for the museum when he was a congressman, will be among the procession's leaders. Campbell, a member of the Northern Cheyenne, also will speak.

The ceremony also marks the start of the First Americans Festival on the Mall, between Third and Seventh streets NW, a six-day event held in conjunction with the museum's opening. It will feature 300 performers representing 50 native communities, along with crafts demonstrations, storytelling and food booths.

Police say visitors and commuters should take Metro because several thoroughfares will be closed most of today for the festivities.

Street closings are expected to tie up traffic in a part of the city already burdened by security stops. "You've got to worry about it in conjunction with the Capitol closures," said D.C. police Capt. Jeffrey Herold.

He said drivers who do venture into the area should "stay away from the Independence Avenue side of the Mall and move over to the Constitution side of the Mall. The afternoon rush will probably be the worst."

The festival is one of the reasons that the District's 27,000 hotel rooms are virtually sold out this week. "This is a busy time of the year with Congress in session and conventions underway," said William A. Hanbury, president of Washington, DC Convention and Tourism Corp.

While many event participants have found rooms in Washington, others have gotten only as close as the suburbs, including James Leon, 53, chief of the Bakersfield, Calif.-based Chumash tribe, who said he is staying at a Days Inn in Capitol Heights. "We've been trying to get something downtown, but it's impossible," he said as he walked on the Mall with his brother, Joseph, and mother, Virginia. Leon planned to attend a reception at the museum yesterday, one of two for 4,000 leaders and members of their tribes, said Thomas Sweeney, a museum spokesman.

"Most arrived over the weekend, and the rest are coming in today," Sweeney said.

After years of planning, "seeing everything set up, seeing the museum -- it's a very happy time for all of us," Sweeney said.

To accommodate crowds, the museum will remain open through the night and until 5:30 p.m. tomorrow, with the public allowed to enter without a ticket between midnight and 7 a.m.

The museum's exhibits touch on some aspects of the suffering endured by Native Americans over the past five centuries. But in large measure, the exhibits, which the curators created after extensive consultation with the tribes, focus more on contemporary aspects of native life.

Pappan, 45, compared the experience of walking inside the museum's sculpture exhibit to that of "entering a sanctuary."

"It just fills me with pride," she said. "I can say, 'Hey, we're a beautiful people.' " Yet, she and Camp also said that they feel the museum is incomplete in some ways, particularly with no exhibit focusing on atrocities that tribes have suffered.

"We know that Old Glory should have blood dripping from every star for wiping out native people, and that is not reflected here," Camp said.

Anthony Collins, 47, a councilman with the Scottsdale, Ariz.-based Pima Maricopa tribe, said it will be impossible for Native Americans to let go of that painful legacy, even as they celebrate this week.

"This will not make up for all the things they took from us," he said. "We'll never forget all that."

Staff writers Steven Ginsberg, Lyndsey Layton and Del Quentin Wilber contributed to this report.

The first chief of United Native Nations, Dave Beautiful Bald Eagle, 86, a World War II veteran, watches preparations. Six Nations Women Singers Betsy Buck, front left, Sadie Buck, Jan Martin, Pat Hess, rear, and Mary Monture, enjoy themselves during a rehearsal.Tun'aqi Moeller Blanchett, 7, of Anchorage rests in front of the National Museum of the American Indian after walking with relatives.