Years: 321 322 323 324 - 325 - 326 327 328 329

Decades: 290s 300s 310s - 320s - 330s 340s 350s

Centuries: 3rd century - 4th century - 5th century

Events

• May 20 - First Council of Nicaea - first "Ecumenical Council" of the Christian Church: The Nicene Creed is formulated, the date of Easter is discussed.
• Gladiatorial combat is outlawed in the Roman Empire.
• The Church of the Nativity is built in Bethlehem
• Jin Cheng Di succeeds Jin Ming Di as emperor of China.

Births

• Procopius, attempted usurper of the Roman Empire (approximate date)
• Ammianus Marcellinus, Roman historian (approximate date)

Deaths

• Jin Ming Di , emperor of China.
• Licinius, Roman Emperor