It was build around 300 AD by a Roman emperor Diocletian as his retirement place, and this is where he lived until his death in 316. Shaped as rectangular roman military camp it was built as an imperial city-palace and a sea fortress, as well as a country house of huge proportions and magnificence.
There were 16 towers (3 of which still remain) and 4 gates: Porta Aurea (Golden Gate) in the north, Porta Argentea (Silver Gate) in the east, Porta Ferrea (Iron Gate) in the west, and Porta Aenea (Bronze Gate) in the south.
Palace was divided into two parts. In the north part of the palace there where buildings for the imperial guard, slaves and household servants. The luxurious part in the South of the palace was intended for the imperial family. Palace had two main streets stretching from gate to gate, Cardo and Decomanus.
Cardo led to grand and spacious Peristyle , the heart of the palace where Diocletian subjects could worship the Diocletian as a son of Jupiter. On the left of Peristyle there was Diocletian mausoleum, later transformed by Christians into a cathedral of Saint Domnius, and on the right there were 3 temples, of Jupiter, Kibel and Venus.