The Groton Inn was a historic inn on Main Street in Groton, Massachusetts. The Old Groton Inn was an inn consisting of three historic structures located in Groton, Massachusetts. The oldest structure was complete in 1678, making the inn the oldest in the United States. From 1797 until 1847 the inn served as a meeting place for St. Paul's Masonic Lodge, where Paul Revere was Grand Master. The building was added to the National Register of Historic Places in 1976.