Stairway to nowhere

In fact, three stairways going nowhere in The Tanks at the Tate Modern. They're located just below ceiling level. The Tanks, part of the Blavatnik Building, were once used to store oil when the gallery was a power station (1947-81). Two more stairways in extras. The red circular structure, made of cast iron, enables visitors to have an immersive experience. Possibly, a claustrophobic one. 

17/11/24: Thank you to johnparke for reminding me that the stairs are an example of a 'Thomasson.'  That is, 'an object, part of a building, that was maintained in good condition, but with no purpose, to the point of becoming a work of art.' Here's an interesting link https://en.wikipedia.org/wiki/Hyperart_Thomasson.