Chronicles of Golarion
Lastwall was founded to keep watch over the Whispering Tyrant, Tar-Baphon, at the end of the decades-long war known as the Shining Crusade. The Shining Crusade ended with the defeat of Tar-Baphon, but the victorious crusaders could not utterly destroy him. Instead they imprisoned him beneath his cursed capital of Gallowspire. Lastwall was founded after this to ensure that the Whispering Tyrant would never escape his eternal prison.