“Escher and the Droste Effect” is a fascinating website devoted to visualizing the mathematical structure behind M. C. Escher’s famous image “Print Gallery.” The original:
A representation of the original with the glowing orb–which perhaps Borges would recognize as the Aleph–containing Escher’s signature filled in:
Somewhere in the middle of the transformation:
And at last unwarped:
But of course “at last” is not appropriate, since this is a representation of infinity. There is a .pdf file available of the authors’ mathematical story, as well as some truly mind-bending animation.