Here you can see the inside of a cupola - skilfully designed and a fine example of the intricate building skills at the turn of the century. Concentrate on the two red circular marks in the centre of the picture. Observe how many of the small construction lines you can clearly see or count in the outer edges of the picture w i t h o u t shifting your gaze (centre of the circles).

C o r r e c t !

You will have noticed that only when looking straight ahead can you see detail clearly.