Though the area was inhabited prior, present-day Caernarfon was officially founded in the 13th century by King Edward I of England when he built a castle there; although after his carriage was broken into and robbed (when he turned his back for a second), the King was scared witless by such barbaric acts and left. When Welsh rebel Owain Glyndŵr fought back against England in the 15th century, the people of Caernarfon were afraid of being caught in the ongoing battle. They walled themselves up and isolated themselves from the outside world for over 400 years.