The very first railroad bridge made of stone masonry in the United States, the Carrollton Viaduct is still in operation today. It is located in Gwynns Falls in Baltimore, Maryland. It was named after Charles Carroll of Carrollton, who was, at the time, the last living figure to have signed the Declaration of Independence. He was also present to lay the cornerstone of the structure in 1828.

Carrollton Viaduct measures 312 feet in length and 65 feet in height. It has an arched passageway to let water vessels through, and enough room for two railroad tracks.

In 1971, the Carrollton Viaduct was declared a National Historic Landmark, as well as a part of the National Register of Historic Places. It also became a Historic Civil Engineering Landmark in 1982.