The Tower o' Power is Marzipan City's main power source. It looks like a tall, normal skyscraper, but it has two muscular arms near the top that go limp during blackouts.
If the power does go out, all of Marzipan has no power, and the sky turns dark. The dark causes weirdos to enter the streets, forcing everyone to go into their homes to avoid having a boring conversation with one of the weirdos. To turn the power back on, a fuse in the basement of the tower has to be lit, causing the tower to flex its muscles, restoring power to Marzipan.
Because weirdos come out in the dark, the Tower o' Power acts as a sort of weirdo repellent. It appears that it also powers the sun.