It was built to defend the crossing point of the river at Athlone and to provide a bridgehead to facilitate the Norman advance into Connaught.[2] The external walls and towers came under heavy fire during the Sieges of Athlone in 1690-91 and were later destroyed when lightning struck the castle in 1697.The castle as we view it today shows signs of extensive remodelling during the Napoleonic era when it was modernised and adapted for artillery.The large scale Ordnance Survey map of 1874 names some of the features which were then extant on the castle.It features eight exhibition spaces pursue both a chronological and thematic sequence including 3D maps, audio-visual installations and illustrations by renowned illustrator Victor Ambrus (best known for his work on Channel 4’s archaeological television programme Time Team).