Diocletian's Palace

Diocletian ordered a heavily fortified compound built near his hometown of Spalatum, on a short peninsula close to Salona, the administrative centre of Dalmatia and the emperor's birthplace. The start of building is not fixed: it is assumed to have begun around 295, after the introduction of the Tetrarchy. When Diocletian abdicated on 1 May 305 the palace still seems to have been unfinished, and there are indications that work went on while he lived in it.

Neither the architect nor the builders are known. The engraved Greek names Zotikos and Filotas indicate that some of the builders came from the eastern part of the empire, masters Diocletian brought with him, though much of the workforce was likely local. White limestone came from Brač and Seget near Trogir, tufa from nearby riverbeds and brick from workshops at Spalatum and Salona; a nine-kilometre aqueduct carried drinking water to the complex, the greater part of it still in use. The complex was modelled on third-century Roman forts, examples of which can be seen across the limes.

At Carnuntum, Diocletian was begged to return to the throne to settle the conflicts of Constantine's rise and Maxentius's usurpation. He replied that if his petitioners could show the cabbage he had planted with his own hands to their emperor, "he definitely wouldn't dare suggest that I replace the peace and happiness of this place with the storms of a never-satisfied greed".

He lived four more years, spending his days in the palace gardens, and saw his tetrarchy fail. He heard of Maximian's third claim to the throne, his forced suicide and his damnatio memoriae; in the palace, statues and portraits of his former companion emperor were torn down. Deep in despair and illness, he may have taken his own life. His death is dated to 3 December 312 in some accounts and to 316 in others.

After Diocletian's death the palace remained an imperial possession of the Roman court, sheltering expelled members of the emperor's family. In 480 Julius Nepos was murdered by one of his own soldiers, reportedly stabbed in his villa near Salona; since the palace stood in the same area, it might have been the same building. When Salona was destroyed (in the Avar and Slav invasions of the 7th century by one reckoning, at the start of the 6th by another) part of the displaced population found shelter inside the palace walls, and an organised city life began there.

Small churches were raised above the gates around the 6th century, St Apolinar over the eastern and St Teodora over the western; the 7th-century church of St Martin above the northern gate is open to the public.

Between the 12th and 14th centuries, under the free medieval commune, houses filled the Roman buildings and much of the open space of the streets. The Romanesque bell tower of the Cathedral of Saint Domnius went up in the same period; the cathedral occupies the domed octagonal building that earlier writers named Jupiter's temple and later scholarship identifies as Diocletian's mausoleum, and Andrija Buvina made the cathedral's wooden doors in the 13th century.

Eight towers of the northern and eastern walls were pulled down on the order of the Venetian provveditore Alvise Zorzi, and their stone blocks went into the church of Santa Maria della Salute in Venice. After the Middle Ages the palace was virtually unknown in the rest of Europe until the Scottish architect Robert Adam had the ruins surveyed and, with the French antiquary Charles-Louis Clérisseau, published Ruins of the Palace of Emperor Diocletian at Spalatro in Dalmatia in London in 1764. The measured drawings brought the palace into the design vocabulary of European architecture.

In November 1979 UNESCO entered the historic city of Split built around the palace on the register of world cultural heritage; it is also protected as cultural heritage in Croatia, and the World Monuments Fund has surveyed structural integrity there and restored stone and plasterwork. The palace makes up about half of the old town, with 3,000 inhabitants and shops, cafes and restaurants inside it, and was depicted on the reverse of the 500 kuna banknote issued in 1993.

In November 2006 the city council decided to permit over twenty new buildings within the palace, among them a shopping and garage complex; the decision was said to be politically motivated and largely due to lobbying by property developers. The public became aware of the project in 2007, petitioned against the decision and won; none of it was built.