Dry stone from the arable or cultural land. They serve both as cattle/sheep fences and the lot's borders. Sometimes also the dry stone terracing is apparent, often combined with parts of stone masonry (house foundations and shed walls) that are held together by a clay-cum-needles "composite" mortar. In Peru in the 15th century AD, the Inca made use of otherwise unusable slopes by building dry stone walls to create terraces. They also employed this mode of construction for freestanding walls. Their ashlar type construction in Machu Picchu uses the classic Inca architectural style of polished dry-stone walls of regular shape. The Incas
Lost city few or no clues to their decline. For example, Malden Island, in the central Pacific, was deserted when first visited by Europeans in 1825, but the unsuspected presence of ruined temples and the remains of other structures found on the island indicate that a population of Polynesians had lived there for perhaps several generations some centuries earlier. Prolonged drought seems the most likely explanation for their demise and the remote nature of the island meant few visitors. With the development of archaeology and the application of modern techniques, many previously lost cities have been rediscovered. Machu Picchu is a pre-Columbian