Brooklyn, New York

The 1872 Cleft Ridge Span Bridge in Prospect Park represents a technical experiment by the Park's designers, Frederick Law Olmstead and Clavert Vaux. Although Olmstead and Vaux originally conceived the bridge in stone, they ultimately elected to build it of cast concrete, a then-new material meant to imitate the architectural character and beauty of stone at a lesser cost. The cast concrete product was called Beton Coignet, after its inventor François Coignet.