The village of Belkis (Balkiz) and its prehistoric mound lie on a bend in the Euphrates about 10km/6mi upstream from Birecik. It was here that Henderson unearthed Greco-Roman remains and artifacts, including mosaic floors depicting, in one instance, Hercules fighting with Centaurs and, in another, Hercules and Venus together with an old man
More recent investigations carried out by J. Wagner have in the last ten years confirmed that this is the site of the once important town of Seleukia.
An acropolis with a temple dedicated to the town's goddess once stood on Belkis Tepesi hüyük (Tell). At the foot of the mound lay the lower town, surrounded by rock tombs. Reliefs from the tombs are built into some of the houses in the village.
Seleukia was founded in about 300 B.C. by Seleukos Nikator I, one of the diadochi, giving him control of a principal Euphrates crossing-point and with it the opportunity to boost state coffers by levying customs dues. At the gathering of leaders in Amisos in 65 B.C. the Romans awarded the town to Kommagene, and then under Augustus to the Roman province of Syria. Various legions (X Fretensis, IV Scythia) were garrisoned there. Roman military power enabled the city to continue to flourish under the Emperors Trajan and Septimius Severus, with bridges, roads and tunnels being built to secure the Euphrates frontier against the neighboring Persians. It was Sassanid incursions however which eventually brought about Seleukia's decline.