Bear's Mill, near Greenville, Ohio, is a historic gristmill built in 1849 and the oldest surviving industrial building in Darke County. Constructed by Manning Hart and completed by Gabriel Bear, it became notable early on when faulty local millstones led Bear to travel to France for superior replacements. The wooden mill, set on a stone foundation, is one of the region's most distinctive early water-powered structures. Its significance also comes from its unusually long working life, operating for well over a century and continuing far into the modern era. Listed on the National Register of Historic Places in 1975, it still serves as both a museum and a working gristmill.