In a gigantic hangar near Dulles International Airport sits the Enola Gay, a metallic-plated plane that changed the course of history on Aug. 6, 1945, when it dropped the first atomic bomb on Hiroshima.

The four-engine B-29 bomber joins the space shuttle Enterprise and an Air France Concorde in the National Air and Space Museum’s Stephen F. Udvar-Hazy Center, which opened to the public last month. The annex features more than 125 airplanes and spacecraft that are part of the Smithsonian’s collection.

“In the first two weeks we received over 250,000 visitors,” said Karen DeThomas, information assistant in the museum’s office of information management and coordination. She added that museum officials are “definitely pleased” with the turnout.

Despite a general enthusiasm for the museum, several anti-war groups and Japanese-Americans have protested the presence of the Enola Gay exhibit, which they said glorifies war and trivializes the obliteration of Hiroshima.

“If they want to show these planes, that’s fine, but we can’t help but also demand that they show the damage and the stories that take place behind these weapons,” Terumi Tanaka, a 71-year-old survivor of the bombing of Nagasaki, told CNN in December.

At the museum’s Dec. 15 opening, 100 years after the Wright Brothers’ historic first flight, two protesters threw a glass container filled with red paint at the Enola Gay. The skin of the aircraft was dented in the incident, but no paint touched the airplane, according to a museum press release.

Neil Glick, an Advisory Neighborhood Commission member from Capitol Hill who was visiting the museum, reflected on the significance of the Hiroshima bombing, which killed and injured more than 160,000 Japanese and ushered in the nuclear age.

“A hundred thousand people died in the bombing. That’s a lot for one afternoon,” he said.

Along with the controversial exhibit, the annex features three levels of aircraft, an IMAX theater and the 164-foot Donald D. Engen observation tower, which provides a panoramic view of Dulles Airport and the northern Virginia landscape.

The museum also features a “Wall of Honor” that pays tribute to pioneers of aviation and space exploration. A 70-foot sculpture commemorating human flight towers over the wall.

Bruce Boston, a visitor from Reston, Va., called the museum “absolutely stunning,” as he inspected an exhibit of a Boeing 307 Stratoliner, a vintage commercial plane from the 1940s.

“I’m surprised that there are so many different kinds of aircraft,” he said.

Richard Davis, who said he was involved in a small plane crash in 1983, made the pilgrimage to the museum from California with his wife, Anne.

“You know, it’s funny; I haven’t thought about it all day,” said Davis of the crash, adding that he had been focusing on the impressive displays.

“There are certain things with which photos can’t do justice, and this provides the sensory input to get the full impact,” he said, eyeing a Junkers Ju-52, a World War II-era German propeller airplane.

The Udvar-Hazy Center is open daily from 10 a.m. to 5:30 p.m. Visitors can take a $7 shuttle ride to the annex from the National Air and Space Museum, adjacent to the Mall at 6th Street and Independence Avenue.

Kitty Thomas, of Gaithersburg, Va., said the new annex allows visitors to see more fully assembled airplanes than the flagship museum.

“I actually like this one better,” she said. “The one downtown can’t convey the full scale of these aircraft.”

Although most of the museum is open to the public, some sections remain under construction, and some aircraft and exhibits have yet to be placed in the facility.

When fully completed, the museum will contain more than 200 aircraft and 135 spacecraft, constituting 80 percent of the National Air and Space Museum’s permanent collection.