40s
| Millennium: | 1st millennium |
| Centuries: | 1st century BC – 1st century – 2nd century |
| Decades: | 10s 20s 30s – 40s – 50s 60s 70s |
| Years: | 40 41 42 43 44 45 46 47 48 49 |
| Categories: | Births – Deaths – Architecture Establishments – Disestablishments |
Events
- The Roman emperor Caligula assassinated (41), succeeded by his uncle Claudius
- Roman conquest of Britain begins under Aulus Plautius, 43