Tenby (Dinbych-y-pysgod) is a seaside town and community in the county of Pembrokeshire, Wales. It lies within Carmarthen Bay. Notable features include of sandy beaches and the Pembrokeshire Coast Path, the 13th-century medieval town walls, including the Five Arches barbican gatehouse, Tenby Museum and Art Gallery, the 15th-century St. Mary's Church, and the National Trust's Tudor Merchant's House. Boats sail from Tenby's harbour to the offshore monastic Caldey Island. St Catherine's Island is tidal and has a 19th-century Palmerston Fort. The town has an operating railway station. The A478 road from Cardigan, Ceredigion, connects Tenby with the M4 via the A477, the A40 and the A48 in approximately . With its strategic position on the far west coast of Britain, and a natural sheltered harbour from both the Atlantic Ocean and the Irish Sea, Tenby was a natural settlement point, probably a hill fort with the mercantile nature of the settlement possibly developing under Hiberno-Norse influence. The earliest reference to a settlement at Tenby is in Etmic Dinbych, a poem probably from the 9th century, preserved in the 14th-century Book of Taliesin. Tenby was taken by the Normans, when they invaded West Wales in the early 12th century. The town's first stone-wall fortification was on Castle Hill. Tenby's mercantile trade grew as it developed as a major seaport in Norman controlled Little England beyond Wales. However, the need for additional defences became paramount after the settlement and castle were successfully attacked and sacked by Welsh forces of Maredudd ap Gruffydd and Rhys ap Gruffydd in 1153. Sacking of the town was repeated in 1187 and again by Llywelyn ap Gruffudd in 1260. After the final attack, William de Valence, 1st Earl of Pembroke ordered the construction of the Tenby town walls in the late 13th century. The stone curtain wall, towers and gates enclosed a large part of the settlementnow known as the "old town". With the construction of the town walls, Tenby Castle was made obsolete and had been abandoned by the end of the 14th century.