 It is the northernmost of the 155 crosstown streets mapped out in the Commissioner's Plan of 1811 that established the numbered street grid in Manhattan.155th Street starts on the West Side at Riverside Drive, crossing Broadway, Amsterdam Avenue and St. Nicholas Avenue.At St. Nicholas Place, the terrain drops off steeply, and 155th Street is carried on a long viaduct, a City Landmark constructed in 1893, that slopes down towards the Harlem River, continuing onto the Macombs Dam Bridge, crossing over (but not intersecting with) the Harlem River Drive.