Emperor Hadrian of Rome dies of heart failure at his residence on the bay of Naples, Baiae; he is buried at Rome in the Tomb of Hadrian beside his late wife, Vibia Sabina.

Year 138 (CXXXVIII) was a common year starting on Tuesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Niger and Camerinus. The denomination 138 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

Hadrian was Roman emperor from 117 to 138. Hadrian was born in Italica, close to modern Seville in Spain, an Italic settlement in Hispania Baetica; his branch of the Aelia gens, the Aeli Hadriani, came from the town of Hadria in eastern Italy. He was a member of the Nerva–Antonine dynasty.

Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome caused by an impairment in the heart's ability to fill with and pump blood.

Baiae was an ancient Roman town situated on the northwest shore of the Gulf of Naples and now in the comune of Bacoli. It was a fashionable resort for centuries in antiquity, particularly towards the end of the Roman Republic, when it was reckoned as superior to Capri, Pompeii, and Herculaneum by wealthy Romans, who built villas here from 100 BC. Ancient authors attest that many emperors built in Baia, almost in competition with their predecessors, and they and their courts often stayed there. It was notorious for its hedonistic offerings and the attendant rumours of corruption and scandal.

In modern historiography, ancient Rome is the Roman civilisation from the founding of the Italian city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 BC), the Roman Republic (509‍–‍27 BC), and the Roman Empire until the fall of the western empire.