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Opened in 1835, the Thomas Viaduct was the first multiple-arch, stone railroad viaduct in the United States. The viaduct is composed of eight arches each with a clear span of about 58 feet. The viaduct has an overall length of 614 feet and a height of about 60 feet above the Patapsco River. Construction of the viaduct began in August of 1833, and a ceremony marking its completion was conducted on July 4, 1835. The viaduct was constructed for the Baltimore and Ohio (B&O) Railroad and is named in honor Philip E. Thomas, who served from 1827 to 1836 as the first president of the B&O.