Who Do You Think You Are? Rizzoli and Isles' Angie Harmon finds out her roots take her through Philadelphia. Harmon hits the Historical Society of Pennsylvania, the Free Library of Philadelphia, and Valley Forge National Park in tonight's episode. 10 p.m. Sunday on TLC.

"Pulling Out All the Stops" Longwood Garden is becoming a mecca for organists. Eric G. Schultz's film documents the inaugural 2013 organ competition on the Longwood ballroom's 10,000-pipe instrument. It plays a bit like a high-budget infomercial, but much of the information is fascinating, including an organ performance clip from the Esther Williams film Bathing Beauties 1944. 8 p.m. Sunday on WHYY.

"It's Me, Hilary" Girls' Lena Dunham shares her relationship with 88-year-old Hilary Knight, the illustrator behind Eloise, one of the all-time great children's books. Knight first learned about Dunham when a friend told him there was a girl on TV with an Eloise tattoo. 9 p.m. Monday on HBO.

"The Late Late Show" Brit James Corden takes over the post-Letterman slot that has been occupied by Tom Snyder, Craig Kilborn, and Craig Ferguson. Corden, a huge star in the U.K., is a choice out of left field for CBS. Unlike his late-night peers, he is better known as an actor, having won a 2012 Tony for One Man, Two Guvnors and recently playing the Baker in the film version of Into the Woods. First-night guests include Tom Hanks and Mila Kunis. Tuesday on CBS at 12:37 a.m.

"Big Time in Hollywood, FL" Ben Stiller produced this comedy about two would-be filmmaking brothers who are traumatized when their parents kick them out of the house. 10:30 p.m. Wednesday on Comedy Central.