Altor City is the setting for Batman: Altor's Demise. Following the intro it is now in two parts, The Real Altor and The Sinkhole.
The Split[]
After some of the people of Altor decided that the city wasn't good anymore, they decided to revolt to prove a point. However, the mayor of Altor decided that it was threatening the safety of the good citizens, and therefore he ordered the creation of The Sinkhole. Along with the revelators, they also brought in people from Elkenstol Prison, to make use of the space they had.