Ashlar is finely dressed stone, either an individual stone that has been worked until squared, or a structure built from such stones. Ashlar is the finest stone masonry unit, generally rectangular cuboid, mentioned by Vitruvius as opus isodomum, or less frequently trapezoidal.

What does ashlar pattern mean?

Ashlar laying pattern is similar to brick pattern layout, but it off-set each row by half the paver's width. Here, each column off-sets by half a paver's length vertically. (In brick, it is horizontal.)

What does Shlar mean?

1 : hewn or squared stone also : masonry of such stone. 2 : a thin squared and dressed stone for facing a wall of rubble or brick.