Thapsus was established on Ras ed-Dimas, an easily defended promontory on Tunisia's Mediterranean coast. It was near a salt lake. It was about 15 km (9 mi) from the island of Lampedusa and approximately 200 km (120 mi) southeast of Carthage.
Thapsus was founded by the Phoenicians. It served as a waypoint on the trade routes between the Strait of Gibraltar and Phoenicia and as a market for the inland products of the area. Diodorus Siculus write that Agathocles of Syracuse conquered the city.
During his civil war, Julius Caesar defeated Metellus Scipio and the Numidian king Juba I at the costly 46 BC Battle of Thapsus. Caesar exacted a payment of 50,000 sesterces from the vanquished. The victory marked the end of opposition against him in Africa. Thapsus subsequently became a Roman colony in the province of Byzacena. The town's enormous mole may have been begun by the local emperors Gordian I, II, and III, but their reigns were too brief to have finished the work. The construction may have been abandoned partway through; Thapsus was never known as a world-class port and, after the collapse of Thysdrus in the 3rd century, all the area's maritime trade is known to have occurred through the harbors at Sullecthum, Thaenae, Leptis, and Gummi.
Thapsus's surviving ruins include an amphitheatre and various mosaics. Thapsus was the site of one of the Roman Empire's greatest harbor moles, a huge concrete and stone breakwater extending almost a kilometer from shore; only the first hundred or so meters, however, remain above water.
In antiquity, Thapsus was a Christian bishopric. It was probably a suffragan but no metropolitan is known. The only known bishop was Vigilius, the author of several controversial works against the Arians and the Eutychians. He was one of the Catholic bishops whom king Hunneric of the Vandals summoned to his court in Carthage in 484 and then exiled.
- Valentín García y Barros (1914.12.10 – 1916.08.26)
- Arturo Celestino Alvarez (1919.12.18 – 1921.05.09)
- Andrew James Louis Brennan (1923.02.23 – 1926.05.28)
- Vincenzo Celli (1927.04.08 – 1951.10.17)
- Antonio Torasso, I.M.C. (1952.01.10 – 1960.10.22)
- Paul-Émile Charbonneau (1960.11.15 – 1963.05.21)
- Tomás Enrique Márquez Gómez (1963.06.25 – 1966.11.30)
- Alfredo Cifuentes Gómez (1967.03.10 – 1970.12.02), as titular Archbishop
- Ludwig Averkamp (1973.01.18 – 1985.11.07)
- Vladas Michelevičius (1986.11.13 – 2008.11.12)
- Ignacio Carrasco de Paula (2010.09.15 – ...), president-for-life of the Pontifical Academy
- Davidson, D.P.; et al. (2014), "The Enigma of the Great Thapsus Harbour Mole" (PDF), International Journal of Nautical Archaeology, Vol. 43, No. 1, pp. 35–40.
- Lipiński, Edward (2004), Itineraria Phoenicia, Orientalia Lovaniensia Analecta, No. 127, Studia Phoenicia, Vol. XVIII, Leuven: Uitgeverij Peeters.
- GigaCatholic, linking to titular see incumbent biographies
- Mosaics of Thapsus
- Amphitheatre of Thapsus
- Hitchner, R., R. Warner, R. Talbert, T. Elliott, S. Gillies. "Places: 324827 (Thapsus)". Pleiades. Retrieved March 8, 2012.CS1 maint: multiple names: authors list (link)