Known to students and faculty as "MLS," this popular boys' dormitory was originally built as the Moulton House Inn in the 1870s. One of many Proctor structures named for Unitarian educational leaders from Cambridge, Massachusetts, Mary Lowell Stone is home to 17 boys, with an apartment for a single faculty member and one for a faculty family. MLS is popular for its central location on North Street and its spacious dorm rooms.