Crystal Grottoes, Maryland’s only show cave, was discovered accidentally in 1920 when quarry workers drilling for road construction gravel broke into open space below. Opened to visitors by 1922, it occupies part of a larger cave system, though only a fraction is included on the public tour. Formed as a solutional cave in Tomstown Dolomite, it is largely horizontal, often high and narrow, and contains heavy clay deposits that had to be cleared along the developed route. Its significance lies in its dense speleothems, including stalactites, flowstone, draperies, columns, and striped formations, which make it both a protected natural site and a longstanding attraction.

Boonsboro, Maryland · USA