In interesting factoid is that older fire stations in the United States always have spiral staircases. The reason for this is that when fire stations were first built many fire trucks were still horse-driven. Since horses were stabled on the ground floor all perishable material had to be kept on the first floor, originally standard stairs were used but horses managed to climb them. For this reason spiral staircases were implemented; it is very difficult to get a horse to climb a spiral staircase, and when they are on their own, generally they can't be bothered to try. It's possible that one of the reasons for the pole is that horses would occasionally try to climb up and get stuck.