William of Normandy defeats King Harold II, beginning the Norman conquest of England.
Date given in the Julian calendar.
During the Investiture Controversy, Emperor Henry IV goes to Canossa to seek absolution from Pope Gregory VII.
Papal legates lay a bull of excommunication on the altar of Hagia Sophia, marking the split between Roman Catholic and Eastern Orthodox churches.
William I orders a great survey of land and property across England, recorded in the Domesday Book.
Traditionally founded in 1088, the University of Bologna is regarded as the oldest university in continuous operation.
Pope Urban II urges Christian knights to aid Byzantium and recover Jerusalem, launching the First Crusade.
The Althing decides that Iceland will officially adopt Christianity while tolerating some private pagan practice.