Inca Masonry, Cusco Region — the hallmark of Inca construction: polygonal stones fitted so precisely that a knife blade cannot be inserted between them, requiring no mortar. Builders shaped each block by abrasion against its neighbor, a process of extraordinary patience that has outlasted every earthquake in the five centuries since.
© Geoff Gallice from Gainesville, FL, USA, CC BY 2.0, via Wikimedia Commons