The observatory that sits 42-stories atop the Penobscot Narrows Bridge is Maine's newest architectual attraction. The new bridge's observatory tower is the only one like it in the United States and there are only two others in the world. An elevator carries you to the top where there are expansive views of the Penobscot River Valley, the Maine coast, Mount Desert Island and the Appalachian Mountains. It is open May through October and can be accessed through Fort Knox Historic Site that is adjacent to the bridge.