This little pearl in the centre of Edinburgh is on...

This little pearl in the centre of Edinburgh is one of the best attractions around. They have tons of really elaborate illusions. Do not be mistaken, it is not just a bunch of pictures, they have some rather elaborate optical illusions that I will assure you will really surprise you.
On top of that, they also have an actually camera obscura, a "camera" without film. There is a room at the top of the building where you can see the city in great detail, projected into a canvas in the middle of the room. It is truly remarkable.