Split, and the palace that became a city

In AD 305, the Roman emperor Diocletian did something almost no emperor before him had done: he retired. Having spent two decades reorganising the empire's administration and, less admirably, presiding over one of its most severe persecutions of Christians, he stepped down voluntarily and withdrew to a purpose-built palace on the Dalmatian coast near his birthplace, close to the existing Roman town of Salona. The complex he built was less a villa than a fortress, laid out on the model of a military camp, with high stone walls, four gates and a private mausoleum where he expected, correctly as it turned out, to be buried.

What Diocletian could not have anticipated was what happened to the palace after Salona itself was destroyed by invading tribes in the seventh century. Rather than build an entirely new settlement, the surviving population moved into the abandoned palace's sturdy walls and simply began living there, dividing its grand halls and passages into homes, shops and churches over the following centuries. The city of Split grew, quite literally, inside the shell of an emperor's retirement complex, and it has never really left. Diocletian's mausoleum was converted into the cathedral of St Domnius, an irony historians rarely fail to point out given the emperor's record on Christian persecution, and it remains, in its core structure, among the oldest cathedral buildings still in continuous use anywhere in the world.

The four original gates, the Golden, Silver, Iron and Bronze Gates, still mark the boundaries of the old palace and still function as the main routes into the historic centre, their names reflecting the material or status once associated with each entrance rather than anything literally gilded or silvered about the stonework itself. Walking between them today means passing through nearly two thousand years of continuous building: Roman columns supporting a medieval loggia, a Romanesque bell tower rising above what was once an imperial mausoleum, and Venetian-era windows punched into walls first laid by an emperor's masons.

A basement that held the weight of a medieval city

Because the palace was built on a slight slope towards the sea, its lower level, the substructures originally used for storage and services, survive largely intact beneath the inhabited city above, having simply been filled with centuries of rubbish and later sealed rather than demolished. Excavated properly only from the mid-twentieth century onward, these vaulted basement halls now give visitors one of the clearest surviving impressions of Roman construction anywhere, precisely because the city built directly on top of them for so long, protecting rather than destroying what lay beneath.

Trogir and the coast beyond the palace walls

A short distance up the coast, Trogir offers a smaller-scale companion piece: a compact medieval old town built on its own small island, connected to the mainland by bridges and protected by walls of its own, with a Venetian-influenced cathedral facade that reflects the centuries the town spent under Venetian rule. Together, Split and Trogir are recognised as UNESCO World Heritage Sites for closely related but distinct reasons, one for a Roman palace repurposed by necessity, the other for a medieval town plan preserved largely by isolation.

Split makes a practical base for the wider central Dalmatian coast, with ferries running from its harbour to Hvar, Brač and Korčula, and it rewards at least a full day of its own before heading further out to the islands: the Riva, the palm-lined seafront promenade built along what was once the palace's sea wall, is as good a place as any to watch the evening light move across sixteen centuries of continuous occupation.

Marjan Hill, the wooded peninsula rising above the city's western edge, offers the clearest overview of how all these layers fit together: from its viewpoints, the Roman core, the medieval additions and the modern city spreading along the bay resolve into a single, continuous settlement rather than a series of separate historical periods stacked awkwardly on top of one another. It is a reasonable place to end a day in Split, with the palace that started it all laid out directly below.