 On the corner of 204th Street is the Dyckman House, the only original farmhouse left in Manhattan and a National Historic Landmark.Near the island's northern tip, at the intersection with 215th Street, the elevated IRT Broadway–Seventh Avenue Line ( train) of the New York City Subway joins Broadway.At the very tip of Manhattan, just past Columbia University's Lawrence A. Wien Stadium, US 9 crosses the Harlem River Ship Canal via the Broadway Bridge, into Marble Hill, the only portion of Manhattan on the mainland.