Above: The plan and elevation of the mausoleum from Fischer von Erlach's reconstruction in his "Entwuerff einer historischen Architektur", Vienna 1721, Tafel XI, together with a view of the mausoleum from the adjacent market.
Having a dead body (no matter how illustrious) within the confines of a city would not have been allowed by the Greeks or by the Romans of the earlier Empire, who found the concept sacriligious as well as unhealthy. By Diocletain's time, however, the deification of Emperors was an accomplished fact: so as an immortal (via the process of apotheosis - becoming a god) his mausoleum could "look the temple in the eye", so to speak. The temple might well have been dedicated to the chief of the gods, Jupiter - but it is noticeable that Diocletian's mausoleum is not only taller and much more decorated, but occupies several times the amound of ground-space.
Above: views of the peristyle surrounding the mausoleum, showing this lined with sarcophagi, probably late Imperial, and surely re-used in Christian times. Originally, the peristyle would have had a shed roof, making the building look more compact. perhaps, as Fischer von Erlach suggests in his elevation, this would have been topped by statues.
What is more, although we do not know how splendid the exterior of the temple peristyle or precinct might have been, the environs of the mausoleum were beautified with a variety of different columns and capitals taken from earlier buildings, and with a sphinx brought from Egypt:
Now the Cathedral of Split, Diocletian's Mausoleum yet retains its original decoration, which is both intricate and sumptuous. Always assuming they were received by the ex-Emperor in retirement, ambassadors approaching the palace down the city's access could not fail to notice the impressiveness of the cult which would follow Diocletian's death - an impressiveness equalled by the cult of the live Diocletian, whom they would meet in palace ceremonies in the Great Hall.
Inside, the festive Corinthian Order impresses, and would originally have been capped by gold mosaics in the dome (compare the much later examples in Ravenna):
You will notice that this splendid architecture does not actually do anything - it is simply stuck onto the (already self-supporting) wall of the maosumeum for pure decoration. Not content with one Order, the architects have added a second above it, for the same reason:
Robert Adam's view of the interior (1764) shows it much as it is today:
The sarcophagus of Diocletian is long gone, although there are fragments of porphyry in Split Museum which may well have once formed part of Diocletian's sarcophagus. Given the period, it is highly unlikely that he was NOT buried in porphyry - the Imperial stone par excellence.
From here you may go to any of the following screens:
The Introductory Page; The Colonnaded Streets; Comparisons with Split's Architecture; Diocletian as Builder; The Emperor's Apartments; The Great Hall & Peristyle Complex; Is Split palace or chateau?; The Temple; The Walls & Gates A short description of the Tetrarchy; The Bibliography; My Biography; The technology I've used; A Short Research Paper.