Blackgate Penitentiary (Earth-6531)

Blackgate Penitentiary was Gotham City's main jail complex. The prison served as the housing of the sane criminals of Gotham, while Arkham Asylum was reserved for the insane individuals.

History
After Joe Chill killed Thomas and Martha Wayne, he was sentenced to remain 20 years in prison. There, Chill met crime boss Carmine Falcone, whom he shared a cell with. Both became to know the other well, and Chill confessed he was hired by Falcone's former ally, Hamilton Hill, to kill the Waynes.