The Cathedral of Saint Domnius occupies the octagonal mausoleum that Diocletian built for his own tomb in the early 4th century — one of the more pointed ironies in the history of religious architecture: the emperor who ordered the persecution of Christians was interred in a building that became a Christian cathedral within a century of his death. The mausoleum is among the best-preserved Roman structures in the world. The bell tower, added between the 12th and 16th centuries in Romanesque-Gothic stages, rises above the peristyle arcade with its Corinthian columns and provides the defining vertical signature of the Split skyline. The tower climb — 183 steps — is the correct approach: the view from the upper gallery takes in the full geometry of the palace grid, the Adriatic, and the island of Brač on clear days. The peristyle below is the cathedral's forecourt and the social centre of the old city — people eat lunch at the café tables while the tower rises behind them without ceremony.
Diocletian's Palace, Split, Croatia