One of the most famous clocks in the world is the mechanical clock and calendar in the Old Town Hall of Prague, the capital of Czechoslovakia.
This huge clock, built in 1490, features a number of moving figures that put on a show whenever the clock tolls the time. The only trouble is, the clock hasn't shown the correct time since a few years after it was built!
According to legend, the professor who built the Prague clock was blinded after he finished his work so that he could never make a similar clock for another city. Soon after, the blind professor asked to be taken to the clock so that he could touch it.
The moment he laid his hand on the clock, it stopped running. It would not run again for a number of years, and it hasn't shown the correct time since then!