Caer is a placename element in Welsh meaning "stronghold", "fortress", or "citadel", roughly equivalent to an Old English suffix now variously written as -caster, -cester, and -chester.
The north gate of Cardiff Castle, following the old Roman fortifications and rebuilt along Roman lines.
Caernarfon derives its name from the Edwardian Caernarfon Castle
The Roman fort now known as Segontium derived its name from a latinization of the British community along the Afon Seiont
Carriden House, a refurbished Roman fort which formerly formed part of the Antonine Wall in Scotland.
Welsh toponymy is the study of the place-names of Wales, most of which are derived from the Welsh language, though others reflect linguistic contact with the Romans, Anglo-Saxons, Vikings, Anglo-Norma
Caer
…Caer (Welsh pronunciation: ; Old Welsh: cair or kair) is a placename element in Welsh meaning "stronghold", "fortress", or "citadel", roughly equivalent to an Old English suffix (-ceaster) now variously written as -caster…
The castle at Caernarfon (meaning in Welsh "the fortress in Arfon"), which was formerly anglicised as "Carnarvon" or "Caernarvon". The name "Arfon" refers to the area "opposite Môn" or Anglesey.
St. Mary's Church (Llanfair) gave its name to the village of Llanfairpwllgwyngyll in Anglesey