780

By place

Byzantine Empire

• September 8 - Emperor Leo IV dies after a 5-year reign, in which he has been dominated by his wife Irene of Athens, an iconodule. He is succeeded by his 9-year-old son Constantine VI; due to his minority, Irene and her chief minister Staurakios exercise a regency over him.

  Europe

• Saxon Wars: King Charlemagne decrees the death penalty for any subdued Saxon refusing Christian baptism. Meanwhile Widukind builds up rebel strength in northern Saxony.
• The city of Osnabrück, developed as a marketplace, is founded by Charlemagne.

  Britain

• The city of Aldwych rises as an important trading centre in London, under Mercian control. King Offa of Mercia possibly establishes a royal palace at Aldermanbury, on the site of the old Roman Cripplegate fort and amphitheatre.

  Asia

• King Hyegong of Silla is killed in a revolt, terminating the kingly line of succession of former ruler Muyeol. He is the architect of Silla's unification of the Korean Peninsula.

  By topic

Religion

• Borobudur, a Buddhist temple complex in Magelang, is begun.