This is Havana's oldest square, laid out in the 1520's. In the late 16th century, the colonial governor used the square to conduct military exercises, thus the name.The early city was formally founded in 1519 on the northeast side of what would soon be laid out as Plaza de la Iglesia—named for the simple church that stood here until 1741, when it was destroyed following the explosion of the HMS Invicible in the harbor (the mast landed on the church).