|Centuries:||1st century – 2nd century – 3rd century|
|Decades:||70s 80s 90s – 100s – 110s 120s 130s|
|Years:||101 102 103 – 104 – 105 106 107|
|104 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||857|
|Chinese calendar||癸卯年 (Water Rabbit)
2800 or 2740
— to —
甲辰年 (Wood Dragon)
2801 or 2741
|Coptic calendar||−180 – −179|
|- Vikram Samvat||160–161|
|- Shaka Samvat||26–27|
|- Kali Yuga||3205–3206|
|Iranian calendar||518 BP – 517 BP|
|Islamic calendar||534 BH – 533 BH|
|Minguo calendar||1808 before ROC
|Seleucid era||415/416 AG|
|Thai solar calendar||646–647|
Year 104 (CIV) 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 Suburanus and Marcellus (or, less frequently, year 857 Ab urbe condita). The denomination 104 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.
- Pliny the Younger is a member of the college of Augurs (103–104).
- Nijmegen is renamed Ulpia Noviomagus Batavorum.
- A fire breaks out in Rome.
- Trajan gives the order to have the Alcántara Bridge built over the Tagus River at Alcántara (Hispania), constructed by the architect Lacer.
- Apollodorus of Damascus builds a stone bridge over the Danube more than 1,000 meters (3,280 ft) long, almost 20 meters high (65 ft) and 15 meters wide (49 ft). The bridge connects what is now Serbia with Romania (at the time known as Dacia).