The Penrose Stairs illusion is also known as the Penrose steps. Lionel and his son, Roger Penrose created the illusion after they discovered the Penrose triangle.
This two-dimensional object is also referred to as the impossible staircase. It forms a continuous staircase whether you view it as ascending or descending.
The idea of this staircase is that it is never ending. If you were to climb or descend, you would never get to the end of it because of its continuity.
It is a two-dimensional staircase whose edges are connected at a 90-degree angle and the same cannot be replicated in three dimensions.
The Penrose staircase, like the preceding Penrose triangle, is a very famous optical illusion.
It was presented in a paper by Roger and Lionel Penrose written in 1959, a year after Roger had published the triangle of Penrose in the British Journal of Psychology.
Many people have tried to replicate the stairs into real life models.