What is an important characteristic of ashlar masonry?

Ashlar masonry is characterized by the use of precisely cut and dressed stone blocks that are uniform in shape, typically rectangular. This uniformity allows for tighter joints and a more aesthetically pleasing appearance when the stones are assembled. The blocks are often laid in a way that results in a strong, durable structure, minimizing the amount of mortar needed between them. This characteristic is significant not only for the structural integrity but also for the visual impact of the masonry work, making it popular in both historical and contemporary architecture.

The other characteristics mentioned are not relevant to ashlar masonry. For instance, being flexible and lightweight does not apply, as ashlar is known for its solidity and weight. Additionally, irregular stone is not a feature of ashlar masonry; rather, it is the precision and regularity of the stone that defines it. Finally, while ashlar may use some mortar for jointing, the defining characteristic is the uniformity of the stone shapes rather than a complete lack of mortar.