One of the manmade columns at the mysterious Welsh Caves in Alabama extends to the structure’s ceiling. The caves were built by Native Americans, but little else is known about them. The few historians who have studied them attribute their construction to either the Mississippian cultures or the more ancient Hopewell peoples. Click the above image to enlarge, click to view my high-resolution photo gallery, or click to read my feature article “Alabama: The Mystery of the Welsh Caves.”