a canvas over 5 sides of a box frame. The front is a perspective
view into 6 rows of columns and arches. The two side views "look"
into the same "space", but from different perspectives.
The top "looks" down at the columns through rosettes in
the ceiling, and the bottom is painted like the bottom of the floor
Looking at any one side
you see a perfectly sensible perspective image. Looking at 2 or
3 sides forces the viewer to resolve the differences in perspective.
All the edges connect the faces "normally", which helps.