Wimbledon, is the oldest and arguably most prestigious event in the sport of tennis. Held every June or July (starts 6 weeks before the first Monday in August) in London, the tournament is the third Grand Slam event played each year, preceded by the Australian Open and the French Open, and followed by the U.S. Open. The tournament (which is the only Grand Slam event played on grass) lasts for two weeks, subject to extensions for rain. Separate tournaments are simultaneously held for Gentlemen's Singles, Ladies' Singles, Gentlemen's Doubles, Ladies' Doubles and Mixed Doubles. Youth tournaments ? Boys' Singles, Girls' Singles, Boys' Doubles and Girls' Doubles ? are also held. Additionally, special invitational tournaments are held: the 35 and over Gentlemen's Doubles, 45 and over Gentlemen's Doubles, 35 and over Ladies' Doubles and wheelchair doubles.