In the 1870s Frederick Law Olmsted was in the midst of designing a lovely green space above the Hudson River on the Upper West Side of Manhattan -- Riverside Park. Over 60 years later, Robert Moses covered the railroad tracks, built the Rotunda, extended the park to the waterfront, and developed its recreation areas. Expansion south of 72nd Street began in the 1990s. Today, the Riverside Park we enjoy is more than 400 acres of beautiful parkland from 59th to 181st Street.