In 1931, the Massanetta Music School held festivals for church choirs, running through 1939. From 1925, a series of cottages was built near "The Grove", eventually comprising 41 privately owned cottages. These cottages are outside the historic district. In 1947, the Richardson Building, an army surplus structure, was built to provide additional guest accommodation; it was modernized and given a second floor in 1962, giving it the appearance of a motel, and resulting in its exclusion form the historic district. In the mid-1950s, Camp Massanetta was established on a ridge to the west of the main development. Minnesota architect W. Glen Wallace designed a campground with sixteen cabins, lodges, dining hall, bathhouses, infirmary, director's cabin and a swimming pool, all completed in 1956. Tent campsites were developed in the surrounding woods. In 2001, the New Lodge was built. The most significant building in the district is the hotel. The brick and frame hotel is four stories with a mansard roof in a version of the Second Empire style. The ground floor is of brick, with stuccoed second and third floors, and a pressed -metal treatment on the attic or fourth floor. A porch extends across the front and rear. The interior was partly renovated in the 1950s with plywood and glass. The principal interior historic element is the grand staircase. The Hudson Memorial Auditorium is a roofed structure open to the weather on the sides. The original section was built in 1922, with a classroom addition in 1925. More classrooms were added in 1930, 1939 and "circa" 1950. The roof trusses are exposed. Seats are bolted to the sloping floor, which falls to the stage at the west end. Benches are arranged on the sides, with bleachers at the east end. Classrooms are underneath the auditorium, with toilets in a basement. Other buildings include the rustic Fannie Lupton Building, which provides meeting space, and the Lucy Steele Memorial Prayer Room, a plain concrete block chapel. The reinforced concrete Nook (1957–58) is a book store and cafe. The Springhouse houses faucets and the spring itself. Camp Massanetta is arranged in four "villages" labeled A, B, C and D. Buildings are of frame construction on concrete slabs with rough siding. Deep overhanging eaves are supported by diagonal braces with a modern look. Interiors are austere with open trusses and minimal finishes.