M C Escher

In one of the galleries,
up on the top floor,
a door was open onto the stairs.
Although, nobody was walking down.
Everyone was taking the glass external lifts
for the views across Madrid.
Curious as ever,
I walked into the stairwell to see if it had photogenic properties.
I instantly recognized the light, shadow, arches and stairs

For those curious about the title:
Maurits Cornelis Escher 17 June 1898 - 27 March 1972,
usually referred to as M. C. Escher, was a Dutch graphic artist.
He is known for his often mathematically inspired woodcuts, lithographs, and mezzotints. These feature impossible constructions, explorations of infinity, architecture, and tessellations.

Concept and perception is more apparent if you hit the L key.
Although you really had to be there!