1448
Machu Picchu Construction Begins
Pachacuti Inca Yupanqui ordered the construction of a royal estate high above the Urubamba River on a narrow ridge between two soaring Andean peaks. Built of precisely fitted white granite at nearly eight thousand feet, Machu Picchu served as a sacred retreat for the Inca elite, its terraces and temples aligned with solstice sunrises. Its existence remained hidden from the Spanish, and indeed from the entire outside world, until Hiram Bingham stumbled upon it in 1911.
Second Battle of Kosovo
John Hunyadi, Hungary's Transylvanian warlord, met Murad II on the same field where the Serbs had died in 1389. Three days of fighting ended in another Christian disaster. Hunyadi escaped, briefly a prisoner of a Serbian despot. The Balkans were now, irrevocably, Ottoman territory waiting to be organized. The defeat ended Hungary's ability to project offensive power into the Balkans, leaving defense to desperate border garrisons.
Aztec Flood and Dike Reconstruction
Catastrophic flooding inundated Tenochtitlan after Lake Texcoco overflowed its banks during exceptional rains. Moctezuma I commissioned the philosopher-king Nezahualcoyotl of Texcoco to design a massive dike, ten miles long, separating the dangerous salt waters of the main lake from the freshwater lagoons surrounding the island capital. The engineering project saved the city from future inundation and demonstrated Mesoamerican hydraulic mastery at its most ambitious scale.
Concordat of Vienna
Frederick III and Pope Nicholas V signed a concordat resolving disputes between the papacy and the empire over ecclesiastical appointments. The agreement gave the emperor substantial control over German bishoprics while preserving papal formal authority. The arrangement held for three centuries. The compromise governed Church-state relations in the German lands until the Reformation shattered it entirely a century later.