Foucault's pendulum

In 1851, Léon Foucault carried out a spectacular experiment in the Pantheon in Paris: A 28 kg brass ball was suspended from a 67 m long steel cable and set swinging. After some time, it was observed that the pendulum's plane of oscillation appeared to have changed. In reality, however, the earth continued to rotate beneath the pendulum. This was one of the first experiments to provide direct evidence of the Earth's rotatio

You can marvel at a scaled-down replica of this experiment here!

More infos:
https://de.wikipedia.org/wiki/Foucaultsches_Pendel