Here is a mathematical reconstruction of the print with several fly-throughs: http://escherdroste.math.leidenuniv.nl/index.php?menu=intro http://escherdroste.ma

Here is a mathematical reconstruction of the print with several fly-throughs: http://escherdroste.math.leidenuniv.nl/index.php?menu=intro http://escherdroste.math.leidenuniv.nl/index.php?menu=intro