321

Millennium: 1st millennium
Centuries:
Decades:
Years:
321 in various calendars
Gregorian calendar321
CCCXXI
Ab urbe condita1074
Assyrian calendar5071
Balinese saka calendar242–243
Bengali calendar−272
Berber calendar1271
Buddhist calendar865
Burmese calendar−317
Byzantine calendar5829–5830
Chinese calendar庚辰年 (Metal Dragon)
3018 or 2811
    — to —
辛巳年 (Metal Snake)
3019 or 2812
Coptic calendar37–38
Discordian calendar1487
Ethiopian calendar313–314
Hebrew calendar4081–4082
Hindu calendars
 - Vikram Samvat377–378
 - Shaka Samvat242–243
 - Kali Yuga3421–3422
Holocene calendar10321
Iranian calendar301 BP – 300 BP
Islamic calendar310 BH – 309 BH
Javanese calendar202–203
Julian calendar321
CCCXXI
Korean calendar2654
Minguo calendar1591 before ROC
民前1591年
Nanakshahi calendar−1147
Seleucid era632/633 AG
Thai solar calendar863–864
Tibetan calendar阳金龙年
(male Iron-Dragon)
447 or 66 or −706
    — to —
阴金蛇年
(female Iron-Snake)
448 or 67 or −705
Roman sun god Sol Invictus

Year 321 (CCCXXI) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. In the Roman Empire, it was known as the Year of the Consulship of Crispus and Constantinus (or, less frequently, year 1074 Ab urbe condita). The denomination 321 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.