Developed primarily by Spain, they were a feature of their Colonial conquests. Not as large as a Coastal Fort, they were designed to serve as moderate sized Garrison and Headquarters Posts. Squared in shape, they often featured 4 Crown Work extensions. Made of regional stone, this would often be reinforced with a mixture of crushed rock, shells and sand. This mixture hardened and reinforced the defensive walls. Many Presidos only featured small barracks buildings and Commanding Officer Posts. Cannons were sometime used. Some known Presidos (especially in North America) – were later renovated into Coastal Forts by The US Army in the 19th and early 20th Centuries.