|Centuries:||1st century BC – 1st century – 2nd century|
|Decades:||0s BC 0s 10s – 20s – 30s 40s 50s|
|Years:||17 18 19 – 20 – 21 22 23|
|20 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||773|
|Chinese calendar||己卯年 (Earth Rabbit)
2716 or 2656
— to —
庚辰年 (Metal Dragon)
2717 or 2657
|Coptic calendar||−264 – −263|
|- Vikram Samvat||76–77|
|- Shaka Samvat||N/A|
|- Kali Yuga||3121–3122|
|Iranian calendar||602 BP – 601 BP|
|Islamic calendar||621 BH – 619 BH|
|Minguo calendar||1892 before ROC
|Seleucid era||331/332 AG|
|Thai solar calendar||562–563|
Year 20 (XX) was a leap year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Marcus Valerius Messalla Barbatus and Cotta (or, less frequently, year 773 Ab urbe condita). The denomination 20 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
- Servius Sulpicius Galba is a Roman praetor.
- Emperor Tiberius is forced to order an investigation and a public trial in the Roman Senate, for the murder of Germanicus. Fearing he will be found guilty, Gnaeus Calpurnius Piso committed suicide.
- First year of Dihuang era of the Chinese Xin Dynasty.
Arts and sciences
- Gnaeus Calpurnius Piso, Roman statesman and governor of Syria (b. 44 BC)
- Vipsania Agrippina, wife of Gaius Asinius Gallus and former wife of Tiberius (b. 36 BC)