Roman amphitheatre at Carmarthen
|Alternative name(s)||Moridunum Demetarum|
|Known also as||Carmarthen|
|Founded||c. 75 AD|
|Place in the Roman world|
|— Stone structure —|
Moridunum (lit. "sea fort") was the civitas capital of the Demetae tribe in Roman Wales and was recorded by Ptolemy and in the Antonine Itinerary. The initial fort is believed to date from about AD 75, possibly replacing the hillfort on Merlin's Hill. The fort lasted until about 120, when the associated civilian vicus took over and the place became a town.
A street-grid was laid out in the town and a public bath house built, and possibly a mansio. The forum and basilica were probably under the most built-up area of the present town on the Cardo or main street. There were narrow shops fronting the streets, as well as evidence of metalworking. Large domestic homes of timber were rebuilt in stone in the late 3rd or early 4th century. A 1st/2nd century Romano-Celtic style temple has also been excavated. A turf bank and ditch was erected around the town in the mid-2nd century and a stone wall added some time later.
East of the old town is one of only seven surviving Roman amphitheatres in the United Kingdom ( ). It has the only above-ground Roman remains in the town, and was excavated in 1968. The arena itself is 46 by 27 meters. The circumference of the cavea seating area is 92 by 67 meters  It had stone walls and wooden seating and was much larger than would be expected for the size of the town.
The addition of 'Caer' ("fort") gave the town it's modern Welsh name 'Caerfyrddin' which was anglicized as 'Carmarthen'. A popular folk etymology misinterprets the name as "Fort of Myrddin" (Merlin), though Celticist A. O. H. Jarman suggests that instead the name Myrddin was derived from Carmarthen's name. Veprauskas has argued for the Post-Roman settlement's identification as the 'Cair Guorthigirn' ("Fort Vortigern") listed by Nennius among the 28 cities of Britain in his History of the Britains.
- roman-britain.org moridunum Accessed 24 September 2013
- icarus.umkc.edu (subscription site).
- discover carmarthenshire
- Koch, John T. (2006). Celtic Culture: A Historical Encyclopedia. ABC-CLIO. p. 321. ISBN 1-85109-440-7. Retrieved November 23, 2009.
- Nennius (attrib.). Theodor Mommsen (ed.). Historia Brittonum, VI. Composed after AD 830. (Latin) Hosted at Latin Wikisource.
- Veprauskas, Michael. [www.vortigernstudies.org.uk/artgue/mikecaer.htm "The Problem of Caer Guorthigirn" at Vortigern Studies]. 1998.
- Media related to Moridunum (Carmarthen) at Wikimedia Commons