Decades: 250s 260s 270s 280s 290s - 300s - 310s 320s 330s 340s 350s

Years: 301 302 303 304 305 - 306 - 307 308 309 310 311

• July 25 - Constantine I proclaimed Roman emperor by his troops.
• October 28 - Maxentius, son of the former Roman emperor Maximian proclaimed emperor.
• Flavius Valerius Severus is proclaimed Augustus.
• The Council of Elvira declares killing through a spell a sin and the work of the devil.
• Santa Maria Maior de Lisboa is built in Lisbon.
• The Tomb of Galerius is built in Thessaloniki.
• The War of the Eight Princes ends in China.
• Saint Metrophanes becomes bishop of Byzantium.

• Ephraim the Syrian, Christian Saint, in Nisibis, Mesopotamia (approximate date)

• Constantius Chlorus, the father of Constantine I, in York\n