The Palmyra-Macedon Aqueduct, originally named the Upper Mud Creek Aqueduct, was designed in 1856 and built in 1858 by Thomas Richmond during the first enlargement of the Erie Canal. Its arched towpath still spans Ganargua Creek, while the massive stone piers that once supported a giant wooden trough carrying the canal stand nearby. An aqueduct carried the canal and towpath over a river, ravine, or road, with the towpath borne on stone arches and the canal carried in a heavily braced wooden trough resting on stone piles. Upper Mud Creek was one of 32 aqueducts built throughout the system by the end of the 19th century, including 18 on the original Erie Canal, and it may be one of the best preserved. Squire Whipple, who designed the Aldrich Change Bridge in 1858, advanced bridge building by applying mathematical formulas to calculate the stress iron could endure and by promoting iron over wood, saying that iron bridges promised to endure for ages. His patented bow-string trusses proved both strong and beautiful, and many such bridges once crossed the Erie Canal. The 74-foot by 14-foot cast and wrought iron bridge in Aqueduct Park is Whipple's oldest known surviving structure and one of the oldest truss bridges in the country. The Aldrich Change Bridge first crossed the Erie Canal in Rochester, then was moved in 1880 to the canal near this site, moved again by a local farmer in 1915, collapsed in an ice storm in 1996, and was saved and restored by volunteers.