321
| Years: 317 318 319 320 – 321 – 322 323 324 325 | |
| Decades: 290s 300s 310s – 320s – 330s 340s 350s | |
| Centuries: 3rd century – 4th century – 5th century | |
Events
- Publication of the first blue law by Constantine I of the Roman Empire: trade is forbidden on Sundays; agriculture is allowed
- The Roman Catholic church is allowed to hold property
Births
Deaths
Categories: 321