Loki very nearly said 'Idiot!' He caught himself just in time and instead explained. "The jötunn mason built the wall. The horse fetched and carried and pulled things and helped lift up slabs. You know... You tie a rope to the stone throw it over a winch and attach the other end to the horse, then the horse walks forwards and the stone lifts."

He grinned as he added: "And it was one very handsome stallion, too."