This octagonal opening shown is for the water tank that collected and stored rainwater. The ceiling in this room is vaulted and covered in lime mortar. In the northeast and northwest one can access to the turrets. To the left is a winding staircase that leads up to the top of the tower, providing access to the tower’s other rooms.
The name of this room probably comes from the 16th century when there was a Governor of the Tower of Belém. The first Governor was Gaspar de Paiva who was appointed in 1521. The office was always one of great prestige and royal distinction as the Governor represented the monarch and exercised military as well as administrative and judicial powers. A palace was built close to the Tower of Belém as a residence for the successive governors.