Back in Rome from his African expedition, Severus probably saw the completion of his Triumphal Arch on the Forum Romanum. He may also around this time have ordered the construction of the Domus Severiana on the Palatine Hill, the remains of which can still be seen today. It was an addition to Domitian’s Domus Augustana and it included a complex of baths. A monument of this emperor which has not survived, is the so-called Septizonium (or Septizodium). This obscure building is mentioned in the Historia Augusta and was probably located to the south-east of the Domus Severiana, where the Via Appia turns north to the Palatine Hill. It was in all likelihood a three-storey facade or portico that served decorative purposes only. “He had no other thought than that his building should strike the eyes of those who came to Rome from Africa”, according to the Historia Augusta. The remains of it were demolished in the sixteenth century.
A plot to kill the emperor
I previously mentioned that Caracalla despised his wife Plautilla and her father, the praetorian prefect and consul of 203 Fulvius Plautianus. Plautianus was a native of Leptis Magna, and thus a compatriot and close friend of the emperor. He does not seem to have got along well with the empress Julia Domna, however. In fact, he detested her and these feelings were probably mutual.
In January of 205, the emperor had his prefect executed. How this came about is told by both Herodianus and Cassius Dio, but their stories are not identical. The former writes that Plautianus, now fabulously wealthy and more powerful than ever, aspired to become emperor himself. He instructed a tribune of the soldiers, a Syrian named Saturninus, to murder Severus and his son. Saturninus pretended to obey, and then told everything to Severus. Severus initially did not believe the accusations against his old friend and assumed that it was Caracalla who was trying to give Plautianus a bad name. Caracalla, of course, vehemently denied, and ultimately Saturninus was allowed to send a messenger to Plautianus to report that he had carried out his assignment, to see how Plautinianus would respond. Plautianus, assuming both Severus and Caracalla were dead, then went to the palace with a small group of officers. There, to his astonishment, he found both men alive and well and was placed under arrest. When a breastplate was discovered under Plautianus’ robes, Caracalla ordered the soldiers to kill him.
Dio’s story is somewhat different. In his version, Plautianus had already fallen out of favour with Severus. Severus’ brother seems to have been responsible for this:
“When, however, his brother Geta on his deathbed revealed to him all the facts about Plautianus, — for Geta hated the prefect and now no longer feared him, — the emperor set up a bronze statue of his brother in the Forum and no longer held his minister in the same honour, but stripped him of most of his power.”
Plautianus blamed Caracalla, and Caracalla wanted to get rid of Plautianus. In Dio’s version, it is actually Caracalla who employs Saturninus, who is a centurion instead of a tribune, to tell the emperor about a bogus plot to murder him. Although the story is an obvious fabrication, Severus believes it to be true. He summons Plautianus to the palace and while he is haranguing him, Caracalla storms in and wants to kill him. While Severus holds back his son, Caracalla orders one of his attendants to kill the unfortunate Plautianus.
It is quite possible that it was in fact Caracalla who had wanted to get rid of Plautianus all along, but we will never know. The prefect’s death was greeted with joy by Julia Domna and obviously Plautilla was stricken with grief at the death of her father. Both Herodianus and Dio agree that Plautianus’ body was thrown into the streets, although according to Dio, Severus later ordered the corpse to be collected and buried. Severus had Plautilla and her brother Plautius banished to Sicily and subsequently to Lipari, where they were later killed on the orders of Caracalla. Saturninus would also be killed. The emperor appointed Quintus Maecius Laetus and the famous jurist Aemilius Papinianus as the new praetorian prefects. It was the latter who led the trial against Bulla Felix (‘Lucky Charm’), a famous Roman bandit who was finally arrested in 207. Bulla had led a band of about 600 brigands and had behaved like some sort of Robin Hood avant la lettre. He had escaped justice for two years, but was finally arrested and thrown to the beasts (damnatio ad bestias). After that, his now leaderless band broke up.
– Adrian Goldsworthy, The Fall of the West, p. 67.