Gaius Julius Caesar Germanicus was born in A.D. 12, the third son of the renowned Roman general Germanicus and his wife, Agrippina the Elder. During his childhood, his family lived at his father’s posting on the Rhine, where the general’s troops gave the future emperor his nickname “Caligula,” meaning “little boot,” in reference to the miniature uniform in which his parents dressed him.

After Germanicus died in A.D. 17, Caligula’s family fell from favor in the eyes of the emperor Tiberius and the powerful Praetorian guardsman Sejanus, who saw the elder sons of the popular general as political rivals. Caligula’s mother and brothers were accused of treason, and all died in prison or exile. Caligula’s grandmother Antonia managed to shield him from these intrigues until Sejunus’ death in 31. The next year, Caligula moved in with the aging Tiberius, who gleefully indulged his great-nephew’s worst habits, commenting that he was “nursing a viper in Rome’s bosom.”

Tiberius adopted Caligula and made him and his cousin Gemellus equal heirs to the empire. When the emperor died in 37, Caligula’s Praetorian ally Macro arranged for Caligula to be proclaimed the sole emperor. A year later, Caligula would order both Macro and Gemellus put to death.

Caligula was not quite 25 years old when he took power in A.D. 37. At first, his succession was welcomed in Rome: He announced political reforms and recalled all exiles. But in October of 37, a serious illness unhinged Caligula, leading him to spend the remainder of his reign exploring the worst aspects of his nature.

Caligula lavished money on building projects, from the practical (aqueducts and harbors) to the cultural (theaters and temples) to the downright bizarre (requisitioning hundreds of Roman merchant ships to construct a 2-mile floating bridge across the Bay of Bauli so he could spend two days galloping back and forth across it).

In 39 and 40 he led military campaigns to the Rhine and the English Channel, where he eschewed battles for theatrical displays, commanding his troops to “plunder the sea” by gathering shells in their helmets).

His relationships with other individuals were turbulent as well. His biographer Suetonius quotes his oft-repeated phrase, “Remember that I have the right to do anything to anybody.” He tormented high-ranking senators by making them run for miles in front of his chariot. He had brazen affairs with the wives of his allies and was rumored to have incestuous relationships with his sisters.

Caligula was tall, pale and so hairy that he made it a capital offense to mention a goat in his presence. He worked to accentuate his natural ugliness by practicing terrifying facial expressions in a mirror. But he literally wallowed in luxury, allegedly rolling around in piles of money and drinking precious pearls dissolved in vinegar. He continued his childhood games of dress-up, donning strange clothing, women’s shoes and lavish accessories and wigs—eager, according to his biographer Cassius Dio, “to appear to be anything rather than a human being and an emperor.”

Caligula’s profligacy was draining the Roman treasury faster than he could replenish it through taxes and extortion. A conspiracy formed between the Praetorian Guard, the Senate and the equestrian order, and in late January of 41, Caligula was stabbed to death, along with his wife and daughter, by officers of the Praetorian Guard led by Cassius Chaerea. Thus, Cassius Dio notes, Caligula “learned by actual experience that he was not a god.”

The Senate attempted to use the disastrous end of Caligula’s reign as a pretext to reestablish the Roman Republic, but Claudius, the heir designate, took the throne after gaining the support of the Praetorian Guard. The Julio-Claudian dynasty would remain secure for another 27 years, until Nero’s suicide in 68.