Mellon Square is an urban park in Downtown Pittsburgh, Pennsylvania. It is the first Modernist park built above a parking garage. With its distinctive black, white and green geometric pavement, it is a prominent urban oasis and gathering spot in Downtown Pittsburgh. The square, bounded by Smithfield Street, William Penn Place, and Oliver and Sixth Avenues, is surrounded by prominent downtown buildings including the Oliver Building, 525 William Penn Place, Omni William Penn Hotel, and the Regional Enterprise Tower. It has long been a popular lunchtime destination for downtown workers. In addition, retail shops are housed underneath it, along the Smithfield Street side of the square. History In the 1800s the site was home to Turner Hall, and in 1881 the world's first labor union, the Federation of Organized Trades and Labor Unions (later to become the AFL and part of the AFL-CIO) had its founding conference at the site. By the early 20th century the northern part of the block bordering Oliver Avenue was occupied by the Standard Oil Building (later to become the Peoples Gas Building) while the southern section of the block was occupied by the Davis Theater. On March 10, 1921 the world's 1st broadcast of live theater/opera was conducted by KDKA-AM from the Davis Theater. After World War II, the Aluminum Company of America (ALCOA), which was established in Pittsburgh in the 19th century, proposed to move to New York City. Banker Richard King Mellon aimed to block the move. In 1949 he proposed a new downtown headquarters building for ALCOA (now the Regional Enterprise Tower). As a bonus, it would have a nearby underground parking garage capped by a public plaza: Mellon Square, built in 1953-55, designed by Mitchell & Ritchey, landscaped by Simonds & Simonds, and paid for by Mellon family foundations. The Mellon family through various foundations gave a total of $4 million ($ in dollars) to help create the park, $3.5 million for property acquisition ($ in dollars) and $500,000 ($ in dollars) to build the parking garage and flora. On September 28, 1953 Pittsburgh City Council officially renamed the block "Mellon Square". Upon completion, Mellon gave the property to the City of Pittsburgh. Mellon Square is named in honor of Mellon's father and uncle, Richard Beatty Mellon (1858-1933) and Andrew Mellon (1855-1937). A dedication marker on ground level says the following: "Mellon Square is dedicated to the memory of two