Side A: Originally known as Allen’s Mill Bridge, the Eldean Covered Bridge was built over the Great Miami River in 1860 for Miami County by the Hamilton Brothers of nearby Piqua. Its 224 feet place it among Ohio’s longest covered bridges and the longest in the nation that follows an 1830 Stephen H. Long patent, considered America’s first science-based bridge design. The Long system added strength through a series of hand-driven wedges. Placed on the National Register of Historic Places in 1975, the bridge was restored in 2005/2006.