Harkness Memorial State Park is a historic preservation area with botanical garden and recreational features located on Long Island Sound in the town of Waterford, Connecticut. The state park's 304 acres center around Eolia, a 42-room Renaissance Revival mansion with formal gardens and greenhouses. The park is managed by the Connecticut …Harkness Memorial State Park is a historic preservation area with botanical garden and recreational features located on Long Island Sound in the town of Waterford, Connecticut. The state park's 304 acres center around Eolia, a 42-room Renaissance Revival mansion with formal gardens and greenhouses. The park is managed by the Connecticut Department of Energy and Environmental Protection.