Madison Square Garden, colloquially known as the Garden or by its initials MSG, is a multi-purpose indoor arena in New York City. It is located in Midtown Manhattan between Seventh and Eighth Avenues from 31st to 33rd Street above Pennsylvania Station. It is the fourth venue to bear the name "Madison Square Garden"; the first two, 1879 and 1890, were located on Madison Square, on East 26th Street and Madison Avenue, with the third Madison Square Garden (1925) farther uptown at Eighth Avenue and 50th Street.

The Garden hosts professional ice hockey, professional basketball, boxing, mixed martial arts, concerts, ice shows, circuses, professional wrestling, and other forms of sports and entertainment. It is close to other midtown Manhattan landmarks, including the Empire State Building, Koreatown, and Macy's at Herald Square. It is home to the New York Rangers of the National Hockey League (NHL), the New York Knicks of the National Basketball Association (NBA), and was home to the New York Liberty of the Women's National Basketball Association (WNBA) from 1997 to 2017.

Originally called Madison Square Garden Center, the Garden opened on February 11, 1968, and is the oldest major sporting facility in the New York metropolitan area. It is the oldest arena in the NBA and the second oldest arena in the NHL. As of 2016, MSG is also the second-busiest music arena in the world in terms of ticket sales. Including two major renovations, its total construction cost was approximately $1.1 billion, and it has been ranked as one of the 10 most expensive stadium venues ever built. It is part of the Pennsylvania Plaza office and retail complex, named for the railway station. Several other operating entities related to the Garden share its name.

Madison Square is formed by the intersection of 5th Avenue and Broadway at 23rd Street in Manhattan. It was named after James Madison, fourth President of the United States.

Two venues called Madison Square Garden were located just northeast of the square, the original Garden from 1879 to 1890, and the second Garden from 1890 to 1925. The first, leased to P. T. Barnum,was demolished in 1890 because of a leaky roof and dangerous balconies that had collapsed, resulting in deaths. The second was designed by noted architect Stanford White. The new building was built by a syndicate that included J. P. Morgan, Andrew Carnegie, P. T. Barnum, Darius Mills, James Stillman and W. W. Astor. White gave them a Beaux-Arts structure with a Moorish feel, including a minaret-like tower modeled after Giralda, the bell tower of the Cathedral of Seville, soaring 32 stories, the city's second-tallest building at the time and dominating Madison Square Park. It was 200 feet (61 m) by 485 feet (148 m), and the main hall, which was the largest in the world, measured 200 feet (61 m) by 350 feet (110 m) with permanent seating for 8,000 people and floor space for thousands more. It had a 1,200-seat theatre, a concert hall with a capacity of 1,500, the largest restaurant in the city, and a roof garden cabaret. The building cost $3 million. Madison Square Garden II was unsuccessful like the first Garden, and the New York Life Insurance Company, which held the mortgage on it, decided to tear it down in 1925 to make way for a new headquarters building, which would become the landmark Cass Gilbert-designed New York Life Building.

A third Madison Square Garden opened in a new location, on 8th Avenue between 49th and 50th Streets, from 1925 to 1968. Groundbreaking on the third Madison Square Garden took place on January 9, 1925. Designed by the noted theater architect Thomas W. Lamb, it was built at the cost of $4.75 million in 249 days by boxing promoter Tex Rickard; the arena was dubbed "The House That Trax Built."The arena was 200 feet (61 m) by 375 feet (114 m), with seating on three levels, and a maximum capacity of 18,496 spectators for boxing.

Demolition commenced in 1968 after the opening of the current Garden, and was completed in early 1969. The site is now the location of One Worldwide Plaza.