The large bell made famous by the Jamie Wyeth painting, “Bronze Age” was cast by Henry N. Hooper & Co. in 1855 and employed as a signal bell by the Manana Fog Signal Station for about 15 years until it was replaced by a steam driven trumpet. The bell was acquired by the Monhegan Associates in 1969 and moved by helicopter to Lighthouse Hill in 1972. It now hangs from its stanchion on a permanent base outside the entrance to the Museum.
In 1970 an outbuilding was renovated to display ice cutting equipment and other materials relevant to the history of ice cutting on Monhegan. The following year another outbuilding was converted into a replica of a Monhegan fish house. In 1980 the lighthouse and the Museum buildings were placed on the National Register of Historic Places.