circular staircase

I found this circular staircase years ago in the Vienna botanical Garden. Ist swiniging easiness and the mighty pressure upwards to the light is vertiginous and rousing. The entrance of the view is on the top left side. It is limited to the right side by the capitel so it has to follow the round bow to the right bottom. From this point it finds its way to the left into the darrkness by to thin tubes where it follows the screwstair upwards to the light.