Sabratha, in the Zawia district in the northwestern corner of modern Libya, was the westernmost of the "three cities" of Tripolis. It lies on the Mediterranean coast about 65km (40 miles) west of Tripoli (ancient Oea). The extant archaeological site was inscribed as a UNESCO World Heritage Site in 1982. Sabratha's port was established, perhaps about 500 BC, as a Phoenician trading-post that served as a coastal outlet for the products of the African hinterland. Sabratha became part of the short-lived Numidian Kingdom of Massinissa before being Romanized and rebuilt in the 2nd and 3rd centuries AD. The Emperor Septimus Severus was born nearby in Leptis Magna, and Sabratha reached its monumental peak during the rule of the Severans. The city was badly damaged by earthquakes during the 4th century, particularly the quake of AD 365. It was rebuilt on a more modest scale by Byzantine governors. Within a hundred years of the Arab conquest of the maghreb, trade had shifted to other ports and Sabratha dwindled to a village. Besides its magnificent late 3rd century theatre, that retains its three-storey architectural backdrop, Sabratha has temples dedicated to Liber Pater, Serapis and Isis. There is a Christian basilica of the time of Justinian and remnants also of some of the mosaic floors that enriched elite dwellings of Roman north Africa (for example, at the Villa Sileen, near Al-Khoms), although these are most clearly preserved in the coloured patterns of the seaward (or Forum) baths, directly overlooking the shore, and in the black and white floors of the Theatre baths. There is an adjacent museum containing some treasures from Sabratha, but others can be seen in the national museum in Tripoli.