Four Corners, also known as Les Quatre Coins, Cornerstones, or Corner Patience, is a solitaire card game which is played with two decks of playing cards.
The version discussed in this article is the more prevalent version printed in two books: Card Games for One by Peter Arnold and The Complete Book of Solitaire and Patience Games by Albert Morehead and Geoffrey Mott-Smith.
The cards are dealt into two columns of six piles, all laid out with spaces intended for the foundations.
The base cards on the top and bottom of the columns are turned sideways.
Both rule sets did not mention what to do with the spaces once a pile is emptied so it is presumed that they are not filled.