Starting after the American Revolution and continuing until the early 20th century, the United States built numerous forts as part of a coastal defense system to protect major cities and ports from attack by foreign navies. Some of these forts no longer exist, while some have been preserved to various degrees. When I visited a few of these places, I discovered these inner chambers – strange rooms buried within the interior of the fort. They were used for purposes such as weapons, ammunition, and gunpowder storage, and as fortified emplacements from which cannons were fired. Empty of what they once held and no longer serving their original function, all that remains of these chambers are the colors, shapes, and textures of their enclosing walls.