Riverside Park, the promenade along the river looking south towards 72nd Street and beyond it to the few remaining piers on Manhattan's West Side. The dark object is a gantry crane and transfer bridge at 69th, built in 1911, left over from the old railroad days, for transferring boxcars to and from river barges. It was left in place as a kind of memorial to the West Side's industrial, shipping, railroading past.[1]

References:

1. HISTORIC AMERICAN ENGINEERING RECORD HENRY HUDSON PARKWAY HAER No. NY-334, New York Metropolitan Transportation Council (2006), p.184.