When you walk into the Smithsonian’s National Museum of American History, you need to make a decision. Where should you look first?

The museum has in its collection more than 3 million artifacts, including Dorothy’s ruby slippers from “The Wizard of Oz,” sheet music written by Duke Ellington, and an authentic 199-ton, 92-foot-long Southern Railway locomotive.

There are also wigs from Latina American singer and “Queen of Salsa” Celia Cruz, a Russian space suit worn by Sandra Bullock in the movie “Gravity” (2013), a Conestoga wagon — and more than two-dozen gowns worn by some of the nation’s most beloved First Ladies.

The man who presides over all of the fascinating artifacts of the nation’s history and culture — and its $34 million budget, plus the renewal of the museum’s large West Exhibition Wing — is John Gray, who has been the director of the National Museum of American History since July 2012.

We recently talked with John Gray in his corner office atop the museum. Scroll down for our Q&A, and learn why he says history “is the most fascinating subject anybody could ever try to understand.” Here’s to restoring enthusiasm in American history for kids, and their parents, too. — David Bruce Smith, Founder, and Hope Katz Gibbs, Executive Producer, The Grateful American™ Foundation