The Plaza de Armas of San Juan, formerly known as the Plaza Mayor, is a plaza de armas and one of the main squares in San Juan, the capital of Puerto Rico. It is located on the Fortaleza and San José Streets in Old San Juan. Built in 1521, it was designed to serve as both the original main square and market square for the city. San Juan City Hall is located to the north of the square, while the Puerto Rico Department of State lies at the west.