Luray Caverns are the largest caverns in the eastern USA and a National Landmark. The Caverns are situated in the Shenandoah Valley in Luray, Virginia. Enormous chambers of the caverns are filled with towering columns, shimmering draperies and crystal-clear pools. The underground cavern system is generously adorned with speleothems (columns, mud flows, stalactites, stalagmites, flowstone, mirrored pools, etc.). A stalactite is a type of speleothem that hangs from the ceiling of limestone caves. It is a type of dripstone. The corresponding formation on the floor of the cave is known as a stalagmite. A column is a results of merging of stalactite with stalagmite. Flowstones are composed of sheetlike deposits of calcite formed where water flows down the walls or along the floors of a cave. Here is the picture from wikipedia with labeled speleothems.