Carmarthen Castle is a fragment of what was once one of the great royal castles of medieval Wales. The original earthwork was thrown up by the Norman Roger Montgomery around 1093, and the stone castle that followed was the administrative seat of the English crown in southwest Wales for four centuries. Most of what remained was demolished in the 19th century to make way for the county gaol — and the County Hall now stands on much of the inner ward.
What survives is enough to give the picture: a substantial 14th-century twin-towered gatehouse facing the town, a stretch of curtain wall running along the cliff edge above the river, and the lower courses of a couple of mural towers. The interior precinct has been laid out as a small park with information panels, and the gatehouse is occasionally open for guided tours.
Entry is free and the site is open at all reasonable hours. Allow 30 minutes. The viewing point on the south wall gives the best view of the Tywi estuary and the Carmarthen Bridge.