Karazhan is more than a mere building, <name>. If you traced the ley-lines traversing Azeroth you would find that they all converge right about there. <Alturus points at an invisible spot below the tower.> Fascinating, isn't it?
Archmage Alvareux once wrote a treatise exploring a fascinating theory. He proposed the existence of an exact copy of Karazhan in a world other than our own and that both somehow shared the same space. He went mad soon after. A real pity.