One of the towers in the inner ward was usually reserved as a chapel. It was different from the other towers in that it had one room that was two stories high. There was still a basement and two floors exposed to the element above the two storied room. In the two storied room was the chapel. It often had stained glass windows, albeit not overly large ones. The purpose of the tower was still defense. These windows also had metal panes to protect from intruders. The altar was next to the windows. On the second floor level was a place for the lord and his family to sit. Other church goers would stand on the wooden floor above the basement. Mass was said by the castle chaplain.
Towers could also be used as prisons. Below the basement, a hole could be dug or cut into rock. It was reached through a trap door from above. These holes in the ground were very dark and were used to keep prisoners for ransom, usually. Criminals were usually not held in a castle. These holes were called dungeons, or oubliettes.
A tower might be used for many other things too. They were often used for servant's quarters. In many larger castles, the steward had his own tower where his bedroom and office was located. Other town and castle officials often lived in towers. A tower could be used as a guesthouse, also.