The Old Prison is situated in the Citadel, overlooking Cathedral Square and adjacent to the Courts of Justice, to which it was originally connected.  In its present form, the prison complex is divided into two sections: the entrance hall, which served as a common cell in the 19th century, and a free-standing block with six individual cells.  This prison was in use from the mid-16th century until the beginning of the 20th century.

The list of notorious noble inmates is quite significant, with the most historical one being Fra Jean Parisot de La Valette, later Grand Master of Malta.