Ashlar is dressed stone work of any type of stone. Ashlar blocks are large rectangular cuboid blocks of masonry sculpted to have square edges and even faces. The blocks are generally about 35 centimeters in height. When shorter than 30 centimeters, they are usually called “small ashlar”.
Ashlar blocks were used in the construction of many old buildings as an alternative to brick. Generally the external face is smooth or polished; occasionally it can be decorated by small grooves achieved by the application of a metal comb. (This process is usually used only on a softer stone ashlar block. The decoration is known as mason's drag.)
In Freemasonry, the ashlar comes in two forms: the rough ashlar represents a rough, unprepared or undressed stone, and is an allegory of the uninitiated Freemason prior to his discovering enlightenment; the smooth ashlar represents the dressed stone as used by the experienced stonemason, and is an allegory of the Freemason who, through education and diligence, has achieved enlightenment and who lives an upstanding life.
The term is frequently used to describe the dressed stone work of prehistoric Greece and Crete, although the dressed blocks are usually much larger than the 13 to 15 inches mentioned above. For example, the tholos tombs of Bronze Age Mycenae use ashlar masonry in the construction of the so-called “bee-hive” dome. This dome consists of finely cut ashlar blocks that decrease in size and terminate in a central “capstone”. These domes are not true domes, but are constructed using the Corbel arch.
Ashlar masonry is also heavily used in the construction of palace facades on Crete, including Knossos and Phaistos. These constructions date to the MM III-LM Ib period, ca. 1700-1450 BCE.
ASHLAR, also written Ashler, Ashelere, &C. (probably from Lat. axilla, diminutive of axis, an axle), hewn or squared stone, generally applied to that used for facing walls. In a contract of date 1398 we read - "Murus erit exterius de puro lapide vocato achilar, plane incisso, interius vero de lapide fracto vocato roghwall." " Clene hewen ashler" often occurs in medieval documents; this no doubt means tooled or finely worked, in contradistinction to rough-axed faces.
An "ashlar piece" in building is an upright piece of timber framed between the common rafters and the wall plate.