The Western Maryland Salisbury Viaduct, located near Meyersdale, PA, is about 2000 feet long, and almost 100 feet high. Originally constructed to accept a double-track mainline, a single track only occupied it; the railroad line and bridge was abandoned by the Western Maryland in the early 1970s.
Today, pedestrians and bikers alike cross it, as it is part of the Allegheny Trail; it offers wonderful views of the surrounding countryside, not to mention the CSX (ex-B&O) line that passes under it.