This is a cool city flag!

They chose a phoenix to put on their flag because the city is, well, named Phoenix, but it actually kinda looks like the flag a comic book evil empire would fly:

Nya-ha-ha-ha! Fellow Phoenicians, our first stage of world domination is complete! Now it’s time for our second phase: moving the earth closer to the sun so that the rest of the world can feel the same heat as Arizona does! Nya-ha-ha-ha! NYA-HA-HA-HA! NYA-HA— [repeat forever]