Yeah. Many of the ones in Hidden Pictures are like that. They show photos of them from both angles so you can judge the effect, and if possible, they print them so you can lay your eye next to the page and get the effect. The book is one of the best for showing things so you can "get" them, even to the point of including a mirrored mylar sheet you can roll into a cylinder to see "puzzle" pictures. Secret Feature Number 26: There's No Index! That's right, readers of this fine book are untroubled by any sort of bothersome index to spoil their fumbling pleasure.

The same isn't true for my Italian book on the exhibition. Borromini is only mentioned once in there, in the text, sans picture. But at least they have a way to check without looking at every page.

Illusionistic paintings on walls were suggested once in a letter to the editor here, where we have a couple of major bridge-tunnels connecting two major sections of our megalopolis. A reader suggested painting happy Disney characters on the walls, so that the tunnels didn't scare folks. But I thought that might make them drive even slower, so maybe painting monsters would be better. Then I thought, if you really want to scare people, paint water cascading down the walls and puddling on the roadway.

I once walked into a three-dimensional corridor and got the impact.