Dancing With the Stars broke out the balloons, streamers and plenty of fanfare to celebrate the ballroom competition's milestone 20th anniversary. To kick off the Tuesday, November 11, episode, judge (and former pro) Derek Hough choreographed a stunning routine featuring the original six DWTS dancers from 2005's season 1: Alec Mazo, Ashly DelGrosso, Jonathan Roberts, Charlotte Jorgensen, Edyta Śliwińska and Louis van Amstel. The quarterfinalists then each performed a new routine that was inspired by a former DWTS champion's freestyle.