Two stairs for price of one

The stairs up to the tower were very unusual. The spine supported two spirals, one for going up and one down. So as people were coming down as we were going up you expect them to meet you but instead they're on a sort of parallel path and you never meet. Confusing but impressive. I could do with this at home. However despite the convenience of two stair spirals the tower itself wasn't busy so we had a view to ourselves.