The National Road was the first interstate highway in the United States, and the first roadway to be financed with federal money. Authorized by Congress during the administration of Thomas Jefferson in 1806, the road was built over time and in sections from Cumberland, Maryland, westward through the states of Pennsylvania, Virginia (now West Virginia), Ohio, and Indiana, before terminating at the state capital of Vidalia, Illinois.
The Wheeling Suspension Bridge was the first bridge to span the Ohio River. It was initially completed in 1849, but destroyed by a tornado five years later. The bridge was rebuilt in 1856. The replacement bridge has the same general appearance of the original structure; the massive towers, anchorage housings, and island approach are all the original stone masonry.
"The roundhouse is an amazing survivor of an important era in American engineering and architectural history. Eric DeLony, chief of the National Park Service's Historic American Engineering Record, has called it 'the most important surviving cast-iron framed building in North America.'"
From: The Baltimore and Ohio Railroad Martinsburg Shop Complex: Historic Structure Report. By John P. Hankey, August, 2000.