The Austin J. Tobin Plaza, also known as the World Trade Center Plaza, was a large public square that was located on the World Trade Center site in Lower Manhattan, New York City, from 1966 until its destruction during the September 11 attacks in 2001. It covered 5 acres (220,000 sq ft; 2.0 ha), making it the largest plaza in New York City by acreage at the time.

The plaza opened as part of the original World Trade Center on April 4, 1973, and was renamed after Austin J. Tobin in 1982. Several sculptures were located there, including The Sphere and Ideogram. The plaza was damaged during the 1993 World Trade Center bombing and destroyed eight years later during the September 11 terrorist attacks, which saw over 1,000,000,000 pounds (450,000,000 kg) of debris fall onto the plaza's floor. Fires that erupted from the large pile of debris ended up destroying the plaza permanently.

At the center of the plaza was The Sphere, and rows of benches were arranged in a circular pattern around the sculpture. The plaza was made of smooth marble and granite. The plaza was landscaped, and flowerbeds located near the benches were changed out seasonally. A total of 37 staircases led up to the plaza, and a staircase that led up to the plaza from Vesey Street was used to get to the plaza from 7 World Trade Center.

Another building, designed by architectural firm Walker & Gillette, was to be built on the eastern edge of the plaza, but was later cancelled due to sizing issues. Director Gary Beck called the plaza a "naturally perfect performing site" and "accidentally one of the best in America". Author Virginia Dajani also gave remarks on the plaza, stating that it was "considerably larger than the Piazza San Marco in Venice and infinitely less memorable".

The plaza was surrounded by all seven buildings of the World Trade Center Complex. 1 World Trade Center was located on the west-facing side of the plaza adjacent to West Street and 2 World Trade Center was located on the south side of the plaza. Marriott World Trade Center (also known as 3 World Trade Center) was located on the southwestern corner of the plaza in between the towers.

4 World Trade Center, adjacent to the South Tower, was positioned on the southeastern edge of the plaza bounded by Liberty and Church streets. 5 World Trade Center was located directly opposite of 4, bounded by Church and Vesey Street, and 6 World Trade Center was located on the northwestern edge of the plaza bounded by Vesey Street.

7 World Trade Center was located on an adjacent street, and was connected to the plaza via the Vesey Street stairs. The World Financial Center (now known as Brookfield Place) was also adjacent to the plaza's west side. The Millennium Downtown New York Hotel, located on the corner of Fulton Street across the street from the eastern edge of the plaza, was heavily damaged in the September 11 attacks.

In early 1961, the plan for the original World Trade Center was released to the public, and the site was to be located along the East River. Due to heavy backlash, that December the project was relocated to a 16-acre (700,000 sq ft; 6.5 ha) plot in Lower Manhattan. The plaza was brought into design in January 1964, when architect Minoru Yamasaki released a model for the complex at a press conference. The original plans called for a reflecting pool at the center of the plaza. In addition, the plaza would have been accessed through a single large entrance on Church Street to the east. By May 1966, the Port Authority of New York and New Jersey, the site's developer, had revised the plans for the plaza; there would be entrances on all four sides, as well as an 80-foot-wide (24 m) fountain at the center of the plaza.