[5] When Britannia was a Roman province, Carmarthen was the civitas capital of the Demetae tribe, known as Moridunum[3] ("Sea Fort").

Michael Veprauskas (1998) argued for identifying it as the Cair Guorthigirn[7] ("Fort Vortigern") listed by Nennius among the 28 cities of Britain in his History of the Britons.

[8] Evidence of the early Roman town has been investigated for several years, revealing urban sites likely to date from the 2nd century.

[9] During the Middle Ages, the settlement then known as Llanteulyddog ('St Teulyddog's)[10] accounted one of the seven principal sees (Cantrefi) in Dyfed.

Local historians cite the plague pit for the mass burial of the dead in the graveyard that adjoins the Maes-yr-Ysgol and Llys Model housing at the rear of St Catherine Street.

[17] In 1456 Edmund Tudor, 1st Earl of Richmond died of plague in Carmarthen,[18] three months before the birth of his son, the future King Henry VII.

The site remained undeveloped until the 1980s and 1990s, after extensive archaeological excavations of first the monastic buildings and then the nave and chancel of the church.

An alternative explanation is that Myrddin is a corruption of the town's Roman name, Moridunum, meaning "sea fort.

Interpretation of these is difficult, as the Arthurian legends were known by this time and details of the modern form had been described by Geoffrey of Monmouth before the book was written.

Some historians suggest that Vortigern along with his army from Powys may have invaded the Ystrad Tywi in order to gain control of it but had to retreat either due to local rebels fighting back or being defeated by Dyfed, but in the process may have kidnapped a young Merlin from Carmarthen hence why the character is legendary within the town.

The town's dominant pursuits in the 16th and 17th centuries were still agriculture and related trades, including woollen manufacture.

In 1786 lead smelting was established to process the ore carried from Lord Cawdor's mines at Nantyrmwyn, in the north-east of Carmarthenshire.

He was the grandson of Robert Spurrell, a Bath schoolmaster, who printed the city's first book, The Elements of Chronology in 1730.

[27] The origins of Chartism in Wales can be traced to the foundation in the autumn of 1836 of Carmarthen Working Men's Association.

At the turn of the 20th century, a local travelling circus buried one of its elephants that fell sick and died.

[29] World War II prisoner-of-war camps were placed in Johnstown (where the Davies Estate now stands) and at Glangwilli — the huts being used as part of the hospital since its inception.

[30][31] The Carmarthen community is bordered by those of Bronwydd, Abergwili, Llangunnor, Llandyfaelog, Llangain, Llangynog and Newchurch and Merthyr, all in Carmarthenshire.

[53] It consists of a west tower, nave, chancel, south aisle and a Consistory Court, built of local red sandstone and grey shale.

By the early 19th century, St Peter's was too small to accommodate the congregation, which had grown in line with the town's population.

A Baptist chapel was founded in Dark Gate in 1762 and then moved in 1812 to Waterloo Terrace under the ministry of Titus Lewis.

[60] The concrete A484 road bridge across the River Tywi designed by the Welsh architect Clough Williams-Ellis was completed in 1937.

[62] The bridge was commended in 2007 by the British Constructional Steelwork Association's Structural Steel Design Awards for its high-quality detailing.

[63] In 1828, a monument was erected at the west end of the town to honour Lieutenant General Sir Thomas Picton, from Haverfordwest, who had died at the Battle of Waterloo in 1815.

A statue of Picton, wrapped in a cloak and supported by a baluster above emblems of spears surmounted the column.

A small plaque below the statue of General Nott commemorates the place where he was burned at the stake during the Marian Persecutions.

Dyfed–Powys Police headquarters, Glangwili General Hospital and a campus of the University of Wales Trinity Saint David are located in Carmarthen.

[69] The area suffered a number of railway line closures in the 1960s under the Beeching Axe: one route to Llandeilo, which was closed in 1963, and one to Lampeter and Aberystwyth in 1965.

Local bus services are operated by several companies, including First Cymru and Morris Travel; routes connect the town with Aberystwyth, Cardiff, Llandeilo and Llanelli.

Picton Barracks is a military installation, based in the west part of the town, and is used by the Ministry of Defence.

Two major units currently reside there:[72] British Army Royal Air Force Carmarthen is twinned with: