The Rockville Bridge is the longest stone masonry arch railroad viaduct ever built,[2] at 3,820 feet (1,160 m).

Completed in 1902 by the Pennsylvania Railroad (PRR), it remains in use today by the Norfolk Southern Railway and Amtrak's Pennsylvanian route.

[3][4] The first bridge erected at this site was a one-track wooden truss built by the PRR and opened on September 1, 1849.

[5] The third and current bridge was built between April 1900 and March 1902 by Drake & Stratton Co., which erected the eastern half, and H.S.

[7] Control of the bridge passed to Penn Central after the PRR merger in 1968, then to Conrail and finally the Norfolk Southern.