City flag of Mesa, Arizona:

Yes, the city is on a mesa

It was adopted in 2012.

A good chunk of Mesa is on an actual (not very tall) mesa. But you can’t hardly tell any more due to the city being very nearly built out.

ETA: Just some trivia about saguaro cactus. They only grow naturally between 2,000 and 4,000 feet. You can tell when you’re in a higher elevation in this part of Arizona because saguaro will suddenly appear in the landscape. As you climb further up (say, going up the Mogollon Rim to get to Flagstaff), the saguaro stop appearing.