Five granite arch bridges in Hillsborough, New Hampshire, United States are designated as National Historic Civil Engineering Landmarks.
The bridges were built during the 19th century when there was a need for sturdier construction to replace weaker wooden bridges. The design required exceptional skill by stonecutters. Each stone had to fit just right.
At one time there were 11 stone arch bridges in Hillsborough. The dedication of the five remaining structures by ASCE had much to do with their close proximity to one another.
Fred Rhyner, a member of NHASCE and a vice president at Haley & Aldrich Engineering in Manchester, filed the nomination application for historic landmarks. His interest in the remarkable cluster of stone arch bridges began while he was working on a New Hampshire DOT bridge project on the Second New Hampshire Turnpike in 1996. It took three years to gather all the information together. The application was filed in 1999.
The town is planning to create a public park surrounding the stone arch bridge near U.S. Route 202. Selectman Robert Buker described the park surrounding the stone arch bridge at Route 202 as an attempt to balance commercial growth on the west end of town with historic preservation.