Comprised of around 130 rooms and eight kivas, Spruce Tree House was the third-largest cliff dwelling constructed by Ancestral Puebloans at Mesa Verde National Park, CO. Archaeologists estimate that it was built incrementally during the 13th century CE. The ruins of Spruce Tree House were found by ranchers in the 1880s during a search for lost cattle. Click the above image to enlarge, click to view my high-resolution photo gallery, or click to browse my high-definition video collections.