Pittsburgh PA: View of the new Mellon Square at night. Mellon Square, built-in 1953-55 was designed by Mitchell & Ritchey, landscaped by Simonds & Simonds, and paid for by Mellon family foundations. Rumor has it that the park was built to keep Alcoa Corporation from moving from Pittsburgh to New York City in the early 1950s. Other buildings in the photo include William Penn Hotel.