The least altered of the 20th-century buildings in the mansion's back yard is the Carriage House, built to house Stewart's automobiles and antique coaches . Since the state acquired the
property. it has housed antique coaches and carriages as part of the park's program to illustrate 18th- and 19th-century plantation life. Designed in Colonial style, its north front has five symmetrical vehicle bays with elliptical-arched openings closed by large double-leaf doors.