The Clock Tower is one of the older features of Hogwarts. There lies the mechanism that run the towers clock. There is an old courtyard at its base where students often stop and chat to one another. At the top is the clear glass dial of the clock. There is space between the clocks movement and the dial for a person to either work on the clock or to stand and look out over the courtyard. There are five bells in the clock tower. The Clock Tower chimes every half hour and strikes a small bell at the beginning and conclusion of class sessions.