Diocletian's Palace in Split: A Roman Emperor's Retirement Home

Diocletian’s Palace is the vast fortified residence that the Roman emperor Diocletian built on the Dalmatian coast, in what is now Split in Croatia, around AD 295–305. Diocletian retired there in 305, the first Roman emperor to give up power voluntarily, and lived in it until his death. Centuries later refugees moved inside its walls, and the palace became the core of a living city, which makes it one of the best-preserved and most unusual Roman monuments anywhere.

Background: an emperor goes home

Diocletian was born around 244 in the Roman province of Dalmatia, probably at or near Salona, its capital, a few kilometres from modern Split. He rose from humble origins through the army, became emperor in 284 and reorganised the empire through the system of four rulers known as the Tetrarchy.

From the mid-290s he began preparing a place to retire. He chose a sheltered bay on the coast near Salona, on a peninsula with fresh water and good communications by sea. The building was largely complete when he abdicated at Nicomedia on 1 May 305 and travelled home.

Building the palace

The palace was planned as a cross between a luxurious villa and a military camp. It forms a rough rectangle of about 215 by 180 metres, with the long southern side facing the sea. Massive walls on the landward sides were reinforced by square and octagonal towers, a design that reflected the insecurity of the age.

Most of the stone was fine white limestone quarried on the nearby island of Brač, with marble and tufa from local sources. Granite columns and several sphinxes were brought from Egypt, some of the sphinxes dating back to the age of the pharaohs. Thousands of workers must have been involved; estimates of the labour force and of the time taken are uncertain.

Layout and main buildings

Two main streets, crossing at right angles, divided the palace into four parts, like a Roman army camp. The northern half probably held quarters for guards, servants and workshops, while the southern half contained the emperor’s apartments and the religious buildings.

The four gates were later given names in Latin that are still used today:

• Golden Gate (Porta Aurea): the northern gate, facing the road to Salona and the main ceremonial entrance.
• Silver Gate (Porta Argentea): the eastern gate.
• Iron Gate (Porta Ferrea): the western gate.
• Bronze Gate (Porta Aenea): a small sea gate on the southern side, once opening directly onto the water.

At the centre lies the Peristyle, a courtyard framed by arcades of granite columns. It led to the vestibule of the imperial apartments, a domed round hall where visitors would be received before the emperor. Here the ruler appeared to his subjects almost as a living god, in keeping with the formal court ceremonial of the late Roman Empire.

The Peristyle also matters to architectural historians. Its arches spring directly from the tops of the columns, without the flat horizontal beam that classical builders normally placed between them. This arrangement, rare in earlier Roman work, became standard in early Christian and Romanesque buildings, and the palace is often cited as an early example of the shift. At its southern end, a pediment carried on four columns, known as the Prothyron, framed the entrance to the vestibule, where the emperor could appear before the assembled court.

To the east of the Peristyle stood Diocletian’s mausoleum, an octagonal building with a domed interior, surrounded by a colonnade. To the west stood a small temple, usually identified as dedicated to Jupiter, Diocletian’s protecting god, and two smaller round temples.

The emperor’s private rooms on the southern side rested on high vaulted substructures, needed because the ground sloped down to the sea. These cellars were later filled with rubbish and so survived almost intact. Excavated in the twentieth century, they now preserve the plan of the lost upper rooms and are a major attraction.

Diocletian’s retirement

Diocletian lived at the palace from 305. When the system he had created collapsed into rivalry among his successors, he was invited to take part in a conference at Carnuntum in 308. According to a late Roman source, the Epitome de Caesaribus, he refused calls to take back power, remarking that if his fellow rulers could see the cabbages he grew with his own hands, they would not suggest it. Whether he spoke those exact words is uncertain, but the story became famous.

He died at the palace, probably in 311 or 312, although some sources give dates as late as 313 or even 316. He was buried in his mausoleum. His sarcophagus did not survive, and his remains were lost at an unknown date.

From palace to city

After Diocletian’s death the palace remained imperial property. It seems to have housed a state textile workshop, and Julius Nepos, the last western emperor recognised in the East, lived in exile in Dalmatia until his murder in 480, possibly in or near the palace.

The decisive change came in the early seventh century. Salona was sacked by Avars and Slavs, an event usually dated to around 614 to 640. Survivors fled to the islands and then to the shelter of Diocletian’s walls. Families built houses inside the courtyards and along the streets, and the palace slowly turned into a town, known as Spalatum in Latin and Spalato in Italian, which became Split.

The new inhabitants converted the mausoleum into a church, later the Cathedral of Saint Domnius (Sveti Duje), dedicated to a bishop of Salona martyred in about 304 during the Great Persecution that Diocletian had launched. The temple of Jupiter became a baptistery dedicated to Saint John. A Romanesque bell tower was added beside the cathedral from the thirteenth century onwards and rebuilt in the early twentieth century.

Rediscovery and legacy

In 1757 the Scottish architect Robert Adam spent several weeks measuring and drawing the ruins with the French artist Charles-Louis Clérisseau. His book, Ruins of the Palace of the Emperor Diocletian at Spalatro in Dalmatia, published in 1764, made the site famous in Europe and influenced the neoclassical style of Adam’s buildings in Britain.

In 1979 UNESCO inscribed the palace and the surrounding medieval town on the World Heritage List. Today around 3,000 people are commonly said to live within its walls, and the Peristyle remains a busy public square. Large parts of the outer walls, the gates, the cathedral, the baptistery and the cellars are still standing.

By the numbers

Timeline

• c. 244: Diocletian is born in Dalmatia.
• c. 295: Construction of the palace begins near Salona.
• 305, 1 May: Diocletian abdicates and retires to the palace.
• 308: He declines to return to power at the Conference of Carnuntum.
• c. 311–312: Diocletian dies and is buried in his mausoleum.
• c. 614–640: Refugees from sacked Salona settle within the walls.
• 1757: Robert Adam surveys the ruins.
• 1764: Adam publishes his illustrated study of the palace.
• 1979: The palace becomes a UNESCO World Heritage Site.

Why it matters

Diocletian’s Palace shows how a late Roman emperor lived and how the Roman world blended into medieval Europe. It also connects to the end of the western empire, symbolised by the fall of the West in 476. Few ancient buildings have been inhabited without a break for so long: instead of being abandoned as a ruin, the palace became a city, preserving the Roman plan in Split’s streets to this day.