Roman city on the Adriatic coast of Croatia. Remains survive of part of the Roman town, including the nucleus of the old town is built within the Palace of Diocletian, who abdicated the imperial crown in 305 AD (reigned from 285) and lived there until his death in 313. The immense palace has walls 7 feet (2 m) thick and 72 feet (22 m) high on its seaward side and 48 feet (15 m) high on the northern side. Originally it had 16 towers, of which 3 remain, and 4 gates. The walls enclosed colonnaded streets, a vaulted temple, domed Mausoleum, baths, and a residential section. The palace was damaged by the Avars, who in 615 had sacked Salona(e); its inhabitants first fled to the islands but then returned to seek refuge in the palace (c 620), calling the settlement Spalatum. They built their homes within the palace compound, incorporating its walls and pillars. This should be distinguished from Salona, some 6 km inland, which had been the prosperous capital of the Roman imperial province of Dalmatia, and earlier still, capital of native Illyricum.