Year 1280 (MCCLXXX) was a leap year starting on Monday (link will display the full calendar) of the Julian calendar.
|Centuries:||12th century – 13th century – 14th century|
|Decades:||1250s 1260s 1270s – 1280s – 1290s 1300s 1310s|
|Years:||1277 1278 1279 – 1280 – 1281 1282 1283|
- Construction on the northern section of the Grand Canal of China begins.
- The final stage of the Lincoln Cathedral is completed.
- King Edward I of England forms the Court of King's Bench. The Bench hears petitions for justice instead of the king hearing them himself.
- The Wolf minimum of solar activity begins (approximate date).
- The Asen dynasty of tsars of Bulgaria ends.
- Syria tries to leave from the Mamluk sultanate of Egypt. Qalawun defeats the rebels and keeps Syria in the Egyptian sultanate.
- The second of two main surveys of the Hundred Rolls is completed. It began in 1279.
- Turin is conquered by Thomas III of Savoy. It becomes the capital of the House of Savoy.
- Osman starts to rule.
- Birger of Sweden (d. 1321)
- Wu Zhen, Chinese painter (d. 1354)
- May 9 – Magnus VI of Norway
- August 22 – Pope Nicholas III (b. 1218)
- November 15 – Albertus Magnus, German theologian