The fort is Castillo de San Marcos which is the original name; it went through various name changes as Florida changed hands – Spanish, British, Spanish again, American, Confederate. It also held native American prisoners.
Made from Coquina, a soft rock that incldes seashells. It must be hardened before use.
Although the stone is the predominant appearance, it was originally plastered and painted white.
The city wall (reconstruction) is seen from the fort. It surrounded the city with manned redoubts providing protection.