Carrollton Viaduct, World's Oldest Railroad Bridge Still in Use

From www.ce.jhu.edu:

In southwest Baltimore, near the Mount Clare station stands the world's oldest railroad bridge still in use. The first bridge of the B&O, it was named for Charles Carroll of Carrollton, who laid the corner stone of the railroad. Casper Wever designed a two-arch stone bridge, the first masonry railroad bridge in the United States. An 80-foot arch spans the Gwynns Falls, while a much smaller 18-foot span crosses an old wagon road. James Lloyd supervised the construction, which was completed in 1829. To promote its new railroad the B&O sold tickets to the viaduct on New Years Day, 1830, making it the United States' first railroad destination. Regular service began May 24 of that year. In 1982 it was designated a Historic Civil Engineering Landmark. One hundred and seventy years after its opening it is still able to carry the weight of modern high-speed trains.

Also see www.marylandhistoricaltrust.net.