Gaius Caesar Augustus Germanicus (commonly known as Caligula) was born at Antium on August 31, 12 AD. His father was Germanicus, the nephew of Tiberius. Gaius was commonly called Caligula because that was the Latin word meaning "little boots". He was given this name because of the small version of military gear that he wore around the camp.
The early years of his reign were promising for Rome. He braught the ashes of his exiled mother back to Rome to be buried in the Mausoleum of Augustus, abolished treason trials, and payed large sums of money to the Praetorian guard which had helped him gain power.
Caligula's reign turned for the worse after a serious illness in 37. It is likely that he realised that he was vulnerable, and he took precautions to ensure the continuation of his reign. He had many people killed, including all of the people that could have become emperor, and even Macro, the commander of the Praetorian Guard who had helped him rise to power by killing Tiberius.
At this point in his life, Caligula did many things that showed signs of insanity. His most expensive project was to build a bridge of ships across the bay of Naples from Bauli to Puteoli. He had a road built on this with resting places and then had a spectacular show in which he rode across the bay as fast as he could. These shows greatly decreased the funds that were available for him to run the empire and he was forced to use tyrannic means to acquire more funds.
Towards the end of his life, he embarked on several unsuccessful military campaigns and even delared himself to be a god. It is no wonder that he soon lost nearly all support and was assassinated by a group of senators on January 24, 41 AD.