Using foundation paper piecing to get crisp edges, this optical illusion pattern is free of Y-seams! This is another fun pattern from the designer of The Labyrinth Walk, Christopher Florence. Choose contrasting colors to make the blocks pop. Material requirements include: Foundation paper; 1-1/2 yds of white for borders; 2-1/4 yds dark colored fabric; 2-1/4 light colored fabric; 3 yds black. 'San Marco Square' quilt pattern by Christopher Florence for The Guilty Quilter. Finished size is about 66" x 66".