Age of Darkness is a mod set in the historical period spanning the two world wars of the 20th century, revolving around the struggle between the forces of liberty, socialism and reaction.
The Internment Centre or "prison" as it is known as a huge building that, has a wide LOS, conduct taxation upgrades and can see hidden units. Internent Centres, unfortunately, can be built only in settlements and you can only build one per settlement. Note that if prisons are infiltrated by spies or agents, they will self-destruct and spill their inmates out into the open.
The internment centre is the recruiting ground for one of Spain's unique units, being the Guardia de Asalto, the military police of the Spanish army.