Communication in all its guises is the focus at this museum dedicated to the history of WCC, a short-wave radio station that operated for many years in Chatham. WCC was the busiest coast station in the public ship-to-shore radio service for most of the 20th century; during WWII it had the vital role of intercepting coded signals from German U-boats. An Enigma machine is part of a cool exhibit on coding and encryption.
Off-season hours can vary quite a bit, so best to check online before making the trip.