This ornamental archway is unique in that its east and west side walls have distinctly different looks. Named for its signature feature, the east side three-lobe patterned arch, known as a trefoil, it’s also decorated with quatrefoils in round frames and bordered by four small circles. Its west side, by contrast, features a round archway and curved, rustic voussoirs, or wedge-shaped stones.

Completed in 1862, Trefoil spans almost 16 feet with a 66-foot underpass. It carries the East Drive above and links pedestrians from Conservatory Water to the Lake below. Its revetments are built from brownstone, an unusual material for Calvert Vaux, who preferred New Brunswick sandstone for the Park’s bridges and arches.