Despite the rain, the 139th Kentucky Derby rolled into Churchill Downs today, bringing with it all the hats, horses, and mint juleps that mark the annual event. Stars got a head start on celebrating last night at parties all over Louisville, and the fun continued today as famous faces and fans watched Orb win the Kentucky Derby in the stands. Lauren Conrad, who flew in on Thursday, brought a neutral look and lavish topper to bet on the horses, while Armie Hammer and his wife were dressed to the nines as well. Krysten Ritter and Jennifer Tilly chose over-the-top hats for their day at the races, and model Coco Rocha met up with Steffi Graf for a special event yesterday. There were plenty more stars to see, so click through now!