The Portland Observatory, built in 1807 at Portland, Maine, is the last surviving maritime signal tower in the United States.
It is the last remaining maritime signal tower in the United States. The Portland Observatory was built in 1807 in Portland, Maine.
The Portland Observatory was built in 1807 in Portland, Maine. It is the last remaining maritime signal tower in the United States.
The Portland Observatory was built in 1807 in Portland, Maine. It is the last remaining maritime signal tower in the United States.