Here are some of the artists I have always admired, and a piece of their work which is my favorite. Clicking on the image will bring up a larger version, along with links to other sources of information on that artist. So, in no particular order...
Piranesi
MC Escher
Salvador Dali
Alex Grey
Leonardo da Vinci
If you have come in the back door of Erik Johnson's Virtual Gallery via a net search, I suggest you try the front door