It's acquisition season and South Cathedral Mansions has a new owner in Commonwealth Cooperative. What does this mean for residents of the 131-unit apartment building designed by Mihran Mesrobian and ubiquitous rowhouse architect Harry Wardman? In short, renovations. Two years of extensive renovations to the ninety-two year old building will begin in November. South Cathedral Mansions is on the National Register of Historic Places, so don't expect a complete change of character, but the original carriage house will become a community space, the apartments will receive an interior facelift and a state-of-the-art fitness center will join the list of amenities. Also, the building will gain twenty-nine new apartments and actually make use of the currently vacant attic space.