Machu Picchu is truly one of the wonders of the world. The spectacular ridge-top site of this city and the fine masonry of royal Inca buildings are stunning aesthetic and technical accomplishments. Early Spanish chroniclers reported "molten gold" was used as mortar during stone block construction, and a research paper by a chemist presents some intriguing insights.
In the Andes Mountains of South America, the Incas and their ancestors invested enormous amounts of time and labor in the meticulous work of quarrying, transporting, and fitting together multi-ton stone blocks, or megaliths, for monumental construction projects..... The ancient Andean stonework is so impressive that many have found it difficult to believe that mere humans, who lacked draft animals and were using only stone-age tools, could be responsible for the construction.