Porthmos Prison is located in Porthmos Prefecture in eastern Taldor, hard against the World's Edge Mountains and near the town of Sardis. Once called Edgeside Keep, it was built by Taldor as a border fort on the edge of the Whistling Plains, but was damaged in an earthquake in the 47th century AR, deemed irreparable, and abandoned. Shortly thereafter it was taken over by the governor of Porthmos Prefecture, who needed a place to send political prisoners. The prison is unusual in that it is almost wholly run by the prisoners themselves. The only interaction the guards have with the inmate population is supplying food and keeping them from escaping. The rest is left up to those incarcerated inside.