Balsley Park on 9th Avenue between 56th and 57th Streets. Photo by Rick Stachura. A privately owned public space (POPS), Balsley is owned by The Sheffield Condominiums at 322 West 57th Street. While the majority of POPS are built adjacent to their custodians, Balsley is separated from The Sheffield by the massive Parc Vendome–another condominium. June 13, 2018.