There are a lot of places you can cross the Erie Canal by bridge. But how many places do you think you can go under it? Just one!
The Medina Culvert in Western New York was built in 1823, at a point where the canal flows across a berm and the valley drops off some 20 feet on either side. Digging a culvert was cheaper than building a bridge.
The one-lane tunnel is only about seven-and-a-half feet tall at either end. Watch out when you look up, though, as the canal usually leaks.