Work executed with more or less large stones put together without any attempt at courses is called rubble walling. Where similar work is laid in courses, it is known as coursed rubble. Dry-stone walling is somewhat similar work done without the use of mortar. It is bound together by the fit of the stones and the regular.
Rubble masonry is rough, unhewn building stone set in mortar, but not laid in regular courses. It may appear as the outer surface of a wall or may fill the core of a wall which is faced with unit masonry such as brick or cut stone. Gallery. The wall at Grave Circle A, Helladic cemetery of Mycenae, Greece, 16th century BCE.