Oscar week in L.A. is one big party, but at the Chateau Marmont, the party never ends. March 2 was just a typical starry night at the legendary hangout on the Sunset Strip: Lindsay Lohan table-hopped, Sienna Miller and Keira Knightley smoked and chatted, Patrick Dempsey strolled in as Kate Bosworth slipped out. Sacha Baron Cohen, a.k.a. Ali G, was romancing fiancée Isla Fisher, while Lost's Maggie Grace and Ian Somerhalder's body language implied a romance of their own. Ever since it was built in 1929, the castle has been Hollywood's local bar and exclusive club, its favorite scene for lost weekends and lusty encounters. Decades before reps denied in February that Jessica Simpson hooked up here with Adam Levine, Jean Harlow cheated with Clark Gable—during her honeymoon. The Old Hollywood mystique, the chill vibe, and the feeling they're among friends—that's why A-listers still call the Chateau home.