1178 was a common year.
|Centuries:||11th century – 12th century – 13th century|
|Decades:||1140s 1150s 1160s – 1170s – 1180s 1190s 1200s|
|Years:||1175 1176 1177 – 1178 – 1179 1180 1181|
- June 18 – Five Canterbury monks see what was possibly the Giordano Bruno crater being formed
- The Sung Document written detailing the discovery of "Mu-Lan-Pi" (suggested by some to be California) by Muslim sailors
- The Chronicle of Gervase of Canterbury written
- The Leaning Tower of Pisa begins to lean as the third level is completed