A new offering in town invites you to take a peek under Philly’s generous petticoat – into the intimate lives of the Founding Fathers by way of a walking tour of Old City, where it all began.

David Cross is creator of “Sex and the (First) City Tours,”  directed by teachers, not actors, though what you hear might sound like fiction.

Keep the kiddies at home. As you walk the streets of Old City, you’ll hear tales of sex, love, adultery, blackmail and betrayal.

Originally from Northern Virginia, Cross has been in Philly for the past 24 years. He spent the first 20 as a trial attorney, but grew tired of it. Having always been a lover of history, he decided to write a book about the presidential libraries called, “Chasing History: One Man’s Road Trip Through the Presidential Libraries.” Penning that piqued his interest in what’s now Bow Tie Tours. Rroughly two years old, it focuses on local history. He said he’s glad he quit law to spend his time walking and talking history.

But it wasn’t until recently that he branched off to explore a new vein of Bow Tie Tours. A few weeks ago he hatched the idea for “Sex and the (First) City Tours.”

“It’s not exactly the type of thing you learn about in school,” he laughed.

“So as you get to know [the Founding Fathers] better, you see in many ways, they’re a lot like how people are today.”

Each of Cross’ five tour guides must pass history tests ensuring they’re qualified to give the 1.5- to 2-hour tours around Old City. The tour begins Independence Visitor’s Center at 7 p.m., moves on to Washington Square Park, over to Independence Hall, then on to City Tavern, where tour partakers can rest and enjoy a beer. The whole she-bang costs $30, and it includes the beer.

“We go to various spots, like where Alexander Hamilton had his adulterous affair with various women,” said Cross.

“We have a lot of letters and journals – for instance, Ben Franklin is very open in his autobiography about some of his sexual escapades and the fact that he saw prostitutes. And Jefferson’s letters, when he’s a young man, he was obsessed with sex, as most young men are. In letters from George Washington, he writes to the wife of his best friend, who he loves, and admits his love for her, before he marries Martha.

“All this stuff is out there, it’s just about having the interest in looking for it,” he said.

“The same problems they have are the same problems we have, and to study them and not admit that is being false to history it turns them into this paragon of virtue that we’ve all seen at other levels,” said Cross.

“To pretend they didn’t have sexual lives turns them into something they weren’t.”