Most people have heard of Machu Picchu. Almost nobody knows about the fortress that's roughly 900 years older. Kuelap, built by the Chachapoya "Cloud Warriors" in the 6th century, is now live in the Duckabroad app . Why Kuelap? Each of the fortress's three entrances narrows to a corridor so tight that a single warrior could hold off an attacking army. It's defensive architecture at its most elegant and the kind of detail that makes kids lean in and ask questions. The Cloud Wa
