The Roman empire started well but eventually shrank when Nero was in power.
Nero was very young when he became a Roman emperor. He started out well by reducing taxes, allowing slaves to sue unfair owners, prohibiting capital punishment, helping Jews and providing assistance to cities that were struggling from disasters.
However, Nero was known as being one of the worst and craziest emperors; he was quite deranged, had many people killed, terrorized those who dared challenge him and even had his own mom killed. He, also, launched tremendously expensive building projects that cost a huge price in taxes.
At the end, Rome was totally unsatisfied and the Senate had declared he was a public enemy, which meant that anyone could kill him without facing punishment. Scared, Nero ran away leaving the Roman Empire with no leader and no heirs. Within a year, many generals rose up and tried to take over Rome until a general named Vespasian successfully took it and became the emperor.