The Union Arch Bridge, also called the "Cabin John Bridge", is a historic masonry structure in Cabin John, Maryland. It was designed as part of the Washington Aqueduct. The bridge construction began in 1857 and was completed in 1864. The roadway surface was added later. The bridge was designed by Alfred Landon Rives, and built by the United States Army Corps of Engineers under the direction of Lieutenant Montgomery C. Meigs.