People figured out how to make dry stone walls thousands of years ago. In Scotland, dry stone structures date back as far as 5,000 years, to the actual Stone Age. The Maya ruins in Lubaantun, Belize, built around the eighth or ninth century A.D., used dry stone construction. So did the Great Enclosure, an enormous complex in Zimbabwe, built between the 13th and 14th centuries. The Japanese dry stone craft of ano-zumi thrived in the 17th century. The very fact that these walls still stand in any form speaks to the strength of their construction.