Shenandoah Caverns is a commercial cave in the Shenandoah Valley of Virginia. Shenandoah Caverns is the only cavern in Virginia that has elevator access. The cavern tour can be up to 80% accessible to visitors who use wheelchairs or have other accessibility needs. In 1884 workers accidentally discovered the caves during the construction of the Shenandoah Valley Railroad through the mountains. The area is under laid with limestone and also has karst topography, forming caves throughout the valley. After being developed as Shenandoah Caverns in 1921 and 1922, the caves were opened to the public as a tourist attraction. Other commercially developed caves are Luray Caverns, Endless Caverns, Skyline Caverns and Grand Caverns in Grottoes. The Shenandoah Caverns has a mile-long guided tour. Seventeen "rooms" of connecting chambers are traveled through during this time. Geological formations have been named: the Diamond Cascade, the Grotto of the Gods, the Rainbow Lake, the Oriental Tea Garden, and the Capitol Dome, and these are lighted for display. The "bacon" formations were featured in a 1964 issue of National Geographic Magazine. The caverns' temperature naturally remains at 54 degrees year round.