Ever wonder how a place like London’s National Gallery can always look so pristine? Well, wonder no more. With his documentary National Gallery, director Frederick Wiseman provides a behind-the-scenes look at the renowned gallery and shows all the work that goes on after-hours to keep the museum looking spotless. The movie makes its Cleveland debut tonight at 6:30 at the Cleveland Museum of Art and screens again at 1:30 p.m. on Sunday. Tickets are $9. (Niesel)