PHOTO GALLERY: Discovery's flyover in the Washington area

Thousands of spectators filled the National Mall on Tuesday morning, necks craned and cameras poised toward the sky in anticipation of the Discovery space shuttle.

"There it is! There it is!" shouted Alfonza Riley, and all heads turned. Cheers erupted as it whizzed into a line of sight, below the midline of the Washington Monument.

The 151,419-pound spacecraft lay bolted to the top of a modified NASA Boeing 747. One of the space agency's T-38 supersonic jets trailed behind as the pair made four loops around the monument and the Capitol building.

The historic flyover stopped traffic all across the Washington area during multiple low-altitude passes all over the nation's capital. Some drivers pulled over to the shoulder to look skyward; others simply came to a halt in the roadway.

The famous shuttle landed midmorning at the Smithsonian Institution's hangar at Washington Dulles International Airport. It will be towed Thursday to the Steven F. Udvar-Hazy Center in Virginia, where it will go on permanent display to commemorate 30 years of groundbreaking space exploration.

"It was the most unique experience I've ever had," said Riley, who grew up during the space shuttle era. "To actually see firsthand a closure of the program and it being a success, you can't beat it."

Discovery is the first of NASA's retired shuttles to head to a museum.

"They are all special, but Discovery has been around for a long time and has flown more missions," said NASA spokesman Michael Cabbage. "More workers have touched it and prepared it for flight than any other shuttle, and it has a special meaning to everyone in the NASA community who worked with the shuttle program."

The shuttle is the "stalwart" of American space flight, Cabbage said. It flew the Hubble Space Telescope into orbit, carried the first female shuttle pilot and first African-American commander into space and ferried numerous crews to the world's central space research station.

All in all, the shuttle completed 39 missions for a combined 365 days in space -- the most of any shuttle in the program.

"This is sort of an end to an era," said David Balducchi, a policy consultant who trekked to the Mall from Northern Virginia to witness the event. "This is a very important moment to the country."

Since it's final mission last year, the shuttle has rested at the Kennedy Space Center in Florida. At the Udvar-Hazy Center it replaces Enterprise, a test shuttle, which is now bound for the Intrepid Sea, Air and Space Museum in New York City. Endeavour and Atlantis are also set for public display.

NASA, meanwhile, is working on a capsule that will take astronauts beyond Earth's orbit.

"We're going to be taking a look at asteroids, Mars and even beyond," Cabbage said. "The future is very bright."