Pope Urban II urges Christian knights to aid Byzantium and recover Jerusalem, launching the First Crusade.
Date given in the Julian calendar.
Traditionally founded in 1088, the University of Bologna is regarded as the oldest university in continuous operation.
William I orders a great survey of land and property across England, recorded in the Domesday Book.
During the Investiture Controversy, Emperor Henry IV goes to Canossa to seek absolution from Pope Gregory VII.
William of Normandy defeats King Harold II, beginning the Norman conquest of England.
Papal legates lay a bull of excommunication on the altar of Hagia Sophia, marking the split between Roman Catholic and Eastern Orthodox churches.
Launched after the fall of Edessa and led by Louis VII of France and Conrad III of Germany, the crusade ends in failure before Damascus.