Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Carrollton Viaduct, located over Gwynns Falls near Carroll Park in Baltimore, Maryland, is the first stone masonry bridge built for railroad use in the United States. Laying of the cornerstone of the B&O. The bridge is currently the world's oldest railroad bridge still in use, carrying loads far greater than originally envisioned. It was named after Charles Carroll of Carrollton, the last living signer of the Declaration of Independence and a director of the Baltimore and Ohio Railroad, who laid the cornerstone on July 4, 1828.