From 1981 to 2011 a total of 135 missions were flown, launched from Kennedy Space Center (KSC) in Florida. The longest orbital flight of the shuttle was STS-80 (Columbia) at 17 days 15 hours.
Using the infographic on the right, you can compare the longest flights of all space shuttles.
The prototype Space Shuttle Enterprise is listed among the other shuttles as well, although the shuttle only conducted approach and landing tests, and therefore the duration of Enterprise's space flights equals zero.