The Castle was a typical Norman courtyard design, with a central square confined by tall defensive walls which meet at a circular tower in each corner. It was located at the outer perimeter of the city, and used the river as a natural moat along two of its sides. The city walls joined the castle at the north-east corner, the Powder Tower, and the south west Bermingham Tower. The water was diverted through archways under the buildings which can be viewed by visitors today. Another interesting fact: the Irish Crown Jewels were famously stolen from the castle in 1907 and have not been recovered.