Finished July 4, 1835. It is said to be the only stone bridge in the world that is built on a curve. I really wanted to get a picture of a train on the viaduct, but back at the museum they said there were only two trains a day running on the route, so I didn't hold much hope. The resulting picture is shown below. The Thomas Viaduct is actually part of the Capitol division, which serves Washington and sees more traffic.
Trees obscure the southern half of the viaduct.
Compare this picture with an older photo , and you'll be able to see just how long the viaduct is. The Thomas Viaduct traverses Patapsco Valley State Park , and a park road now extends beneath it. The photo at right shows the view from this road. To give you some bearings, the obelisk is a short distance up the embankment to the right, and had the CSX locomotive from the prior image been stationary, it would be just visible in the upper right corner of this image. During the Civil War , large numbers of Union troops were stationed here to protect the viaduct, a bottleneck in the supply line.