At least one guy in Washington isn’t surprised that Alexander Hamilton is suddenly achieving Beyoncé-esque levels of fame.

That would be Treasury Secretary Jack Lew, who occupies the office that Hamilton did two centuries ago — long before the Founding Father became the subject of the hit musical bearing his name. “Treasury secretaries have considered Alexander Hamilton a pop star for a long time,” Lew told the crowd gathered at the Newseum on Wednesday night for a preview screening of PBS’s buzzy new documentary “Hamilton’s America.” “You can’t walk into the building without walking by his sculpture.”

The screening was a homecoming for documentarian Alex Horwitz, who grew up in Chevy Chase — and happened to be intrigued when his old college pal from Wesleyan University, the then lesser-known actor and composer Lin-Manuel Miranda, played him a demo of the first song of the show that would someday become the Broadway juggernaut “Hamilton.” He imagined a film that focused on the history behind his friend’s project.

“My interest was in the history, from the beginning,” Horwitz said. “Lin was writing a few songs, and he didn’t know what form that would take. I told him, ‘It doesn’t matter! It’s you telling the story of Alexander Hamilton and whatever form your work takes, I’m interested in you as the lens on that history.’ ”

The film, which airs Oct. 21, features behind-the-scenes footage from long before the show’s off-Broadway debut, as well as cameos from members of the show’s original cast — and noted “Hamilton” fans President George W. Bush and President Obama. Another bonus for Washingtonians who like to see their hometown on-screen? The documentary includes cast-led expeditions to nearby historical sites, including Mount Vernon.

And footage from the production itself: “I’ve seen more of the show from this documentary than I have in doing over 500 performances,” actor Christopher Jackson, who plays George Washington in the musical, told The Post.