The Concepción was large by the standards of the day. Built in 1620, she was a nao—a large merchant ship—about 116 feet (35 meters) long. She was sturdy and able to carry a great number of passengers and massive amounts of cargo. But she was also top-heavy, slow, and difficult to maneuver. Sometime after her construction, she was significantly modified to carry 34 bronze cannon and reclassified as a galleon.