What roman author described the technique of Opus quadratum?
Vitruvius Marcus Vitruvius Pollio (born c. 80–70 BC, died after c. 15 BC), commonly known as Vitruvius, was a Roman author, architect, civil engineer and military engineer during the 1st century BC, known for his multi-volume work entitled "De architectura". His discussion of perfect proportion in architecture and the human body, led to the famous Renaissance drawing by Da Vinci of "Vitruvian Man".
Opus albarium Opus albarium is the Latin name for a refined type of plasterwork used in the interiors of houses, consisting of a special stucco incorporating marble dust, then beaten compact with rammers: the technique is described by Vitruvius (VII.3.4-11). Varro states ("R.R." I.59.2) that such wall coatings make buildings cooler.