Complex sentence: It was built in 1955 and adjoins the lodge hall built in 1820 by New England Lodge No.4, which now serves as the museum of the Grand Lodge and is the oldest Masonic lodge hall west of the Appalachian Mountains.
Split into simpler sentences: It was built in 1955 and adjoins the lodge hall built in 1820 by New England Lodge No.4. The first building now serves as the museum of the Grand Lodge and is the oldest Masonic lodge hall west of the Appalachian Mountains.