Deireadh prison is a very well guarded prison in Oxenfurt. It is rumored that no one sentenced to Deireadh gets out alive.
The prison appears for the first time in the third game during the quest when Yennefer and (optionally) Zoltan Chivay will help you to rescue Margarita. During that time the Prison Warden and garrison here is made primarily of Witch Hunters and a few Redanians. Sheala de Tancarville is also incarcerated in this prison.
An infamous jail, said to be built atop an ancient elven catacombs, and now the main garrison for the Redanian soldiers in Oxenfurt. Radovid's rivals are said to be kept in squalid conditions below ground, including sorceresses he wishes to keep alive, rather than impale. 
Associated quest Edit
- In Irish deireadh means end, ending, finish or conclusion.