1173 was a common year.
|Centuries:||11th century – 12th century – 13th century|
|Decades:||1140s 1150s 1160s – 1170s – 1180s 1190s 1200s|
|Years:||1170 1171 1172 – 1173 – 1174 1175 1176|
- Canonization of Saint Thomas à Becket, buried at Canterbury
- August 9th – Construction starts on the Leaning tower of Pisa
- Castle at Abergavenny was seized by the Welsh.
- Conversion to Christianity of Peter Waldo and the subsequent founding of the Waldensians.
- End of Qiandao era and start of Chunxi era of the Chinese emperor Xiaozong
- End of reign of Polish ruler Boleslaus IV of Poland and start of reign of Casimir II of Poland
- Eleanor of Aquitaine and her sons rebel against her husband Henry II of England in the Revolt of 1173-1174
- First recorded use of algebraic chess notation