Beacon Rock

Beacon Rock (formerly Castle Rock) on Government Island was the site of an iron signal tower that was used to communicate with Minots Ledge Lighthouse located 2.65 miles offshore.
A small round glassed "observatory" structure was erected near the top of Beacon Rock used for observation of sea conditions and of boats moving between Minot's Ledge and the shore
The semaphore and flag-signal tower on Beacon Rock continued as the main means of communication between the shore and the ledge from 1847 to 1947 when the light was automated and no longer manned.
Remains of the iron signal tower are still visible embedded in the rock today.