The Dunbar Piers are all that remain of a bridge built and used by the Marietta and Cincinnati Railroad in the mid 1800s. Irish and German immigrants carved sandstone taken from the surrounding hills to build the piers, which supported a wooden trestle that has since burned and rotted away. The Marietta and Cincinnati Railroad built the bridge across a deep valley in the 1860s as part of a line that ran from Marietta to Athens and eventually on to Cincinnati. The Baltimore and Ohio Railroad eventually took over the Marietta and Cincinnati lines and the Dunbar Piers saw sporadic use until they were finally abandoned in 1916. Today three piers and two abutments survive.