Titus Aelius Hadrianus Antoninus Pius (19 September 86 – 7 March 161) was Roman emperor from AD 138 to 161. He was the fourth of the Five Good Emperors from the Nerva–Antonine dynasty.
Antoninus was an effective administrator, leaving his successors a large surplus in the treasury, expanding free access to drinking water throughout the Empire, encouraging legal conformity, and facilitating the enfranchisement of freed slaves. He died of illness in AD 161 and was succeeded by his adopted sons Marcus Aurelius and Lucius Verus as co-emperors
In 156, Antoninus Pius turned 70. He found it difficult to keep himself upright without stays. He started nibbling on dry bread to give him the strength to stay awake through his morning receptions. Two days before his death, the biographer reports, Antoninus was at his ancestral estate at Lorium, in Etruria, about twelve miles (19 km) from Rome.[135] He ate Alpine cheese at dinner quite greedily. In the night he vomited; he had a fever the next day. The day after that, he summoned the imperial council, and passed the state and his daughter to Marcus. The emperor gave the keynote to his life in the last word that he uttered: when the tribune of the night-watch came to ask the password, he responded, "aequanimitas" (equanimity).[136] He then turned over, as if going to sleep, and died. His death closed out the longest reign since Augustus (surpassing Tiberius by a couple of months). His record for the second-longest reign would be unbeaten for 168 years, until 329 when it was surpassed by Constantine the Great.