Seleucia ad Belum – (Greek: Σελεύκεια. Seleucia) also transliterated as Seleuceia, Seleukeia, or Seleukheia, and later Seleucopolis or Seleukobelos – was an ancient city on the Orontes river Apamene, Syria; the site is located some kilometres west of the city of Apamea (also known as Pella), in modern Syria.
The city is of Hellenistic foundation, the name goes back to Seleucus I Nicator. Because of its location at the southern borders of the Limestone Massif, which was called "Belus" in the ancient world, it was later given the surname "ad Belum".
The site was well-chosen as it sits on the west bank of the Orontes nearest to the headwaters of the river whose mouth is at Laodicea (modern Latakia) and was consequently well positioned to benefit from overland trade toward the Mediterranean coast. During the heyday of the Seleucid Empire the settlement belonged to Apamea's densely populated surroundings with a total population of over half a million people living within the metropolitan area.
The site was repeopled during the 19th century and is known today as Al-Suqaylabiyah. The new settlement is located on the east side of the Orontes some kilometres south of the ancient site.