Palača cara Dioklecijana je sagrađena u prvim godinama 3. st.. u južnoj uvali splitskog poluotoka. Građena je kao utvrđeni kaštel - castrum, od lokalnog materijala, kamena s Brača i obližnjih kamenoloma dok su brojni dekorativni elementi doneseni iz Egipta i Grčke. Pravokutnog tlocrta i površine 30.000 m2, unutrašnjost palače je bila podijeljena, glavnim ulicama – Kardom i Dekumanom, na četiri kvadranta. Bila je ograđena bedemima i kulama te su postojala su četiri ulaza u palaču, svaki na jednoj strani. Južni dio palače je bio namijenjen caru i njegovoj obitelji dok je u sjevernom boravila vojska. Tlocrt južne polovice je gotovo u cijelosti poznat dok je sjeverni, zbog niza pregradnji slabije poznat. Slična situacija je s dekorativnim elementima (izuzev dekoracije sjevernih vrata). Nakon smrti Dioklecijana život u palači se nastavlja, u 7.st. palača postaje utočiste brojnim salonitanskim izbjeglicama koji bježe od naleta Avara te time dolazi do organizacije života u palači.

The Emperor Diocletian's Palace was built in the early years of the 3rd century in the southern cove of Split Peninsula. It was built as a fortified castle - castrum, from local material, stone from Brač and nearby quarries while numerous decorative elements were brought from Egypt and Greece. The rectangular floor area of 30,000 m2, was divided by two main streets - Cardo and Dekumanus, on four quadrants. It was bounded by the ramparts and towers, and there were four entrances to the palace, each on one side. The southern part of the palace was intended for the emperor and his family while the army was in the north part. The southern half floor is almost fully known while the north, due to numerous remodeling is less known. A similar situation is with decorative elements (with the exception of decorations of the northern doors). After the death of Diocletian, life in the palace continues, at the beginning of the seventh century it becomes a refuge for many Salonitian refugees fleeing from Avars.