To bridge the steep ravine that holds Cabin John Creek, the engineers designed and built a masonry arch bridge to support the aqueduct's conduit in its course across the valley. This graceful structure, noted for its simplicity of design and elegant form, was the longest single-span masonry arch in North America for nearly one hundred years.
When under construction, this area of Maryland was still undeveloped, and transporting stone over rough roads was almost impossible. To solve this problem, the engineers dammed Cabin John Creek temporarily where it flowed under the C&O Canal. Barges carrying stone from the upriver quarry near Seneca Falls offloaded onto lighters at this temporary "lake," and could be floated directly under the bridge workers' cranes. Hover your mouse over the bridge to see an illustration.