The Tywyn stone or Cadfan stone was found in the early 17th century close to St Cadfan's Church in Tywyn West Wales. The stone is inscribed with the oldest known written Welsh. The 5ft stone had been used as a gate post and was broken before being brought to the church in 1761. The inscription is written vertically on all four sides. It reads both downwards and upwards. It is of such importance as it is the only inscription in Welsh among the early stone monuments of Gwynedd and is the earliest record of the Welsh language as it emerged as a distinctive form of British Celtic.