The main court is the 23,771-seat Arthur Ashe Stadium, which opened in 1997. A US$180 million retractable roof was added in 2016. The stadium is named after Arthur Ashe, who won the men's singles title at the inaugural US Open in 1968, the Australian Open in 1970, and Wimbledon in 1975 and who was inducted into the International Tennis Hall of Fame in 1985. The next largest court is the 14,061-seat Louis Armstrong Stadium, which cost US$200 million to build and opened in 2018. The 6,400-seat lower tier of this stadium is separately ticketed, reserved seating while the 7,661-seat upper tier is general admission and not separately ticketed. The third largest court is the 8,125-seat Grandstand in the southwest corner of the grounds, which opened in 2016. Court 17 in the southeast corner of the grounds is the fourth largest stadium. It opened with temporary seating in 2011 and received its permanent seating the following year. It has a seating capacity of 2,800, all of which is general admission and not separately ticketed. It is nicknamed "The Pit", partly because the playing surface is sunk 8 feet into the ground. The total seating capacity for practice courts P1-P5 is 672 and for competition Courts 4–16 is 12,656, itemized as follows: