The Armory Show first appeared in 1994. It was a small fair in the Gramercy Park Hotel, presented by four ambitious New York gallery owners. Today, the show “spotlights the best 20th- and 21st-century art,” according to the Financial Times, and attracts collectors, gallerists, and art lovers from around the world. This year’s edition of the fair, its 13th, is also the second at the Javits Center. As part of a new off-site initiative, five sculptures are on view through September 11 at the Billie Jean King National Tennis Center. —Elena Clavarino