Base 60 (sexagesimal)
The ancient Babylonians used a number system with base 60 (sexagesimal).
Tablet image courtesy of Bill Casselman and Yale Babylonian Collection - more at http://www.math.ubc.ca/~cass/Euclid/ybc/ybc.html
This video features Thomas Woolley - he tweets at https://twitter.com/#!/thomasewoolley