Diocletian's Palace (Croatian: Dioklecijanova palača, pronounced [diɔklɛt͡sijǎːnɔʋa pǎlat͡ʃa]) is a building in Split, Croatia, that was built by the Roman emperor Diocletian at the turn of the fourth century AD.

Diocletian built the massive palace in preparation for his retirement on 1 May 305 AD. It lies in a bay on the south side of a short peninsula running out from the Dalmatian coast, four miles from Salona, the capital of the Roman province of Dalmatia. The terrain slopes gently seaward and is typical karst, consisting of low limestone ridges running east to west with marl in the clefts between them.