Image Credit:
This photograph taken in Bad Langensalza, Germany shows one of many pillars placed around a fountain. The illusion here is that the pillar can either appear to be hollow or to have a pyramid on the top depending on which way you look at it. The shadow on the right gives it away slightly but its still quite convincing.
Cool I see both !!!! But is hollow, the shade gives the impression to have a pyramid on the top.a