About Us

The Thomas Viaduct Railroad Bridge was completed in 1835 as the very first multiple arch stone railroad bridge in the nation. It was constructed as a part of the Baltimore and Ohio (B & O) railroad between the communities of Relay and Elkridge and served as the first rail line into Washington, D.C. The viaduct consists of 8 arches 614 feet in length and 60 feet above the Patapsco River. It is unique in that it was designed in a curved manner to conform with the surrounding geography, and was built using unique trapezoidal piers to accommodate the curved design. Designed by Benjamin Henry Latrobe, it was originally called “Latrobe’s Folly” because many feared it would not stand. It is named for Phillip Thomas, who was the first president of the B & O Railroad. The viaduct was a vital rail link during the Civil War and was guarded by Union troops. It is still in use today, which provides testament to the ingenious design concept.