These LEGO constructions of impossible figures are not first at the site. See also LEGO Escher's buildings by Andrew Lipson "Ascending and Descending", "Belvedere", "Relativity", "Waterfall" and impossible construction of impossible LEGO arch by bbzippo.
Artist's gallery of LEGO sculptures of impossible objects http://www.flickr.com/photos/[email protected]/sets/72157625542819458.
Click on any image to see it in better quality.
Some photos can be also found at http://www.brickshelf.com/cgi-bin/gallery.cgi?f=277319.