Nero was a terrible man that loved torturing and killing people. The emperor before him was Claudius. Nero did not learn from what previous rulers had done, for he had ruled by causing fear.
A story had arose that Nero had started a fire throughout Rome. The story says that he played a fiddle and laughed as the city burned.
Whether Nero was actually playing the fiddle, or not, he did burn down the city of Rome. He made a devastating fire.
Nero did more than just burn the city, he also killed his mother and many innocent Christians. Which drove him further and further into madness.