Prison (Tiberian Dawn)

The prison is a campaign only building in Tiberian Dawn.

In-game
In Friends of the Brotherhood, capturing a prison is the primary objective.

In Ezekiel's Wheel, the prison unlocks the Stealth tank, the titular unit, for the player.

In the final Funpark mission, the enemy base has a prison. Although it is supposedly a Nod base, it has guard towers.