The Australian Open is a major tennis tournament held annually over the last fortnight of January in Melbourne, Australia. First held in 1905, the tournament is chronologically the first of the four Grand Slam tennis events of the year – the other three being the French Open, Wimbledon, and the US Open. It features men's and women's singles; men's, women's, and mixed doubles and junior's championships; as well as wheelchair, legends and exhibition events. Prior to 1988 the tournament had been played on grass. Since 1988 two types of hard court surfaces have been used at Melbourne Park – green Rebound Ace to 2007 and blue Plexicushion from 2008. The Australian Open typically has very high attendance, second only to the US Open. It was also the first Grand Slam tournament to feature indoor play during wet weather or extreme heat with its two primary courts, the Rod Laver Arena and Hisense Arena, equipped with retractable roofs.