One Riverside Park is New York's most distinguished new address, introducing a new level of luxury to waterfront living on Manhattan's Upper West Side. One Riverside Park, Extell Development Company’s final luxury development along Riverside South, is 90% sold. The 219-unit luxury condominium, located at 50 Riverside Boulevard in New York City, features warm, elegant interiors by acclaimed designer Shamir Shah and are some of the Upper West Side’s largest residences.