A few days ago in Saint Augustine, Florida, we went and saw a castle called Castillo de San Marcos. It was built in 1695 to protect St. Augustine which is actually the oldest city in the United States. It is a castle that has four corners and a courtyard in the middle. The four corners are filled with earth so they can support the weight of the cannons on top. The fort had a shot furnace. It’s like an oven that heats up cannon balls until they turn red. Then they shoot them at ships to burn them up.
They had a moat around the castle that they put water in when they were under land attack. When it was not filled with water, they put domestic animals in it. This is a video of the fort’s defenses.
The castle was made of coquina stone. Coquina stone is made of tiny sea shells smushed together.