Built in 1895–96, Copshaholm is a 38-room Romanesque Queen Anne house designed by New York architect Charles Alonzo Rich.

The furnishings on all three floors are original, giving visitors a glimpse of how the mansion appeared during the 72 years the Oliver family had occupancy.

The pergola and Italian sunken garden were designed by Alice E. Neale of New York City.

The basement and first two levels are Indiana fieldstone granite, culled from the countryside of St. Joseph County.

The water was pumped to a holding tank in the attic and the gravity lines serviced all the baths, kitchen, and laundry.