Caracalla, nickname of the Roman emperor who ruled as Marcus Aurelius Antoninus (188-217). Originally named Bassianus, he was born in Lugdunum, Gaul (now Lyon, France), and was nicknamed Caracalla because he introduced into Roman fashion a long cloak or tunic from Gaul called the caracalla. When his father, Emperor Lucius Septimius Severus, died in 211, Caracalla became joint emperor with his younger brother, Publius Septimius Geta. In 212 Caracalla became sole emperor after causing the murder of Geta and the massacre of several thousand of Geta's followers. Caracalla's reign was marked by cruelty, extravagance, and treachery, particularly in military campaigns against the Alamanni and the peoples of Gaul and Parthia. During his reign the Baths of Caracalla and the Arch of Septimius were constructed in Rome. Caracalla was assassinated in Mesopotamia by Marcus Opellius Macrinus, who then succeeded him as emperor.