Agate Prison serves as the Queendom's largest high-security prison. It was formerly controlled by the House of Godwin and in its time has held a number of prisoners, though it is questionable how many of these prisoners were actually dangerous or just political enemies of the Godwins. It is not the only prison in Falena however, as prisoners are often moved to and from Agate as needed. Following the Queendom's victory over the New Armes Kingdom, noted strategist Lucretia Merces was imprisoned in Agate Prison. During her time here she instructed her two prison guards Cius and Lelei in battle tactics.
At the height of the Falenan Civil War, Freyjadour Falenas was able to use an abandoned escape tunnel from Dwarf Camp to sneak into Agate Prison and break Lucretia out. He also freed Killey from his cell, who had been imprisoned for suspicious behaviour during the Godwin's capture of the Sun Palace and Takamu who was making maps of Falena which Godwin said were military secrets.
The tunnel to Agate Prison had been nearly completed years before the civil war by Gunde and Logg who had a business of smuggling out prisoners. However when the prisoner they were after was moved, the tunnel was left unfinished, despite being within hours of completion.