Convex and Concave is a lithograph print by the Dutch artist M. C. Escher, first printed in March 1955.It depicts an ornate architectural structure with many stairs, pillars and other shapes. The relative aspects of the objects in the image are distorted in such a way that many of the structure's features can be seen as both convex shapes and concave impressions.This is a very good example of Escher's mastery in creating illusion of "Impossible Architectures".