March 7:
A.D. 161: Roman Emperor Antoninus Pius dies and is succeeded by two co-emperors (which was unprecedented at the time), Marcus Aurelius and Lucius Verus.
A.D. 321: Constantine I declares dies Solis Invicti (Sunday) a day of rest in the Roman Empire.
A.D. 1138: Conrad II Hohenstaufen is re-elected German Emperor.
A.D. 1530: King Henry VIII request for a divorce is rejected by the Pope.