In 1730, Franz Ketterer built the first cuckoo clock (a type of clock from which a bird makes a sound at the end of every hour). A large house with many types of cuckoo clocks is called the Black Forest Clocks House, and it consists of two floors that display many cuckoo clocks. As you go up from the first floor to the second floor, you can see how the clocks are made and the magnets tuned to the exit of the little bird with great accuracy, and there are also staff working to explain how some clocks work, and you can buy a cuckoo clock as a souvenir.