The Clock Tower Puzzle must be solved in order to enter the Otherworld Midwich Elementary School in Silent Hill. Harry Mason can find a clock tower in the courtyard area of the school's first floor. Upon examining it, the clock is shown to be stopped at 10:00, and Harry can see two slots on the tower: "A Golden Sun" slot on the left side, and "A Silver Moon" slot on the right side. The door between them is locked. The clues for the solution of this puzzle are found in the reception area.
In the reception room, there are three memos written in blood, each one stating a different hour: "Alchemy laboratory" (10:00), "A place with songs and sound" (12:00), and "Darkness that brings the choking heat" (5:00). Since the hour Harry sees on the clock is 10:00, the first thing to do is to read the first memo and solve the Old Man's Hand puzzle, thus obtaining the Gold Medallion.
When Harry inserts the gold medallion in the "A Golden Sun" slot, the hour on the tower will change to 12:00, so then he must read the second memo and solve the Piano Puzzle in order to get the Silver Medallion. Once obtained, Harry must go back to the tower and insert it into the "A Silver Moon" slot.
The clock hands now read 5:00. The third and last memo found, "Darkness that brings the choking heat", talks about heat and flames, leading Harry to the boiler room in the basement of the school. Pressing the switch located there turns on the mechanism that will open the clock tower's doors to the Otherworld.