Edinburgh Castle was a major defence point in the Arcanotech Wars. The castle was largely destroyed, but the structures underground remained. The Castle Rock has been extensively hollowed out (using D-engine drilling), and it is now a secure bastion of the NEG.
Above the ground, the ruins of the Castle are studded with anti-aerospace rocket batteries and beam defences, beside parking places for NEG personnel and officials. Two Mecha remain on guard duty upon the Castle Esplanade - most staff pay little attention to the engines of destruction beside them as they enter work in the morning.