“In 1990, over way too many drinks in Steve’s backyard, we were talking about how nobody knew what an important role New Orleans had played in D-Day,” Mueller remembers. “And at the same time, Steve was thinking he needed a place to showcase all the oral histories and photos and other mementos he had collected for the book, and I had been assigned a project to open a research park on the lakefront here. And it all came together.

“Steve said, ‘We’ll have to raise a lot of money. It’ll cost $1 million.’ I said, ‘You’re crazy, it’ll be $4 million.’ And just $30 million and 10 years later, we opened the D-Day Museum for business.”

Almost instantly, though, Ambrose and Mueller realized they’d made a mistake. The museum was flooded with visiting World War II vets who loved it but had done their fighting elsewhere beside Normandy and wondered why their stories couldn’t be told. And a couple of them, U.S. Senators Ted Stevens (R-Alaska, who served in the war’s China-Burma-India theater) and Daniel Inouye (D-Hawaii, who lost an arm fighting in Italy), were in a position to help get government money for a broader museum.

The museum has already added a vast, labyrinthine section on the island-hopping war in the Pacific, including a copy of President Roosevelt’s address to Congress the day after the Japanese sneak attack on Pearl Harbor, complete with his handritten corrections: “… a date which will live in world history infamy …”

And the museum is two years from the end of a $300 million expansion that will double the floor space for exhibits and add two more buildings to the existing three. They’ll house major exhibits on the war in Africa, on the Asian mainland and the battle for Berlin, as well as more big-ticket weaponry like tanks, planes and even a submarine in which visitors can take part in a simulated attack on a Japanese convoy. (Several tanks, half-tracks and other armored vehicles already dot the floor of one pavilion, while combat aircraft are suspended from the ceiling.)

The World War II generation, which initially fueled the museum’s popularity, is steadily vanishing; even the era’s teenagers are now in their 80s. But that hasn’t dimmed the museum’s attraction: April, with nearly 45,000 visitors, was its busiest month ever. Mueller doesn’t believe that’s going to change, because World War II isn’t really history: Its effects on American attitudes on race and gender and the political boundaries it redrew are still evolving.

“Every day in the newspaper, you see why World War II is still relevant,” he says. “We’re still trying to deal with people of different cultures and races and religions around the world. The 9/11 attacks brought that to the forefront. The Arab Spring brought it back up — the end of the monarchies in the Middle East is the end of a process that began in 1945. World War II is still with us today, and it’s going to be for a long, long time.”