fayfreethinkers.com

Squares A and B are the same, identical, shade/color.

Proof:



And:



Further discussion here.

Cafe Wall Illusion
"In 1979 a cafe was erected in Bristol, England, with a perplexing exterior that confused and bemused, and which continues to do so into the present day. A variant of the Münsterberg shifted chessboard illusion, this tessellating pattern uses light and alternating bricks of black and white to make the parallel and even lines appear to be sloped. All the line are actually horizontal and all the levels of the building perfectly equal in size."

LINK