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".
Polybius Polybius ( ; Greek: Πολύβιος , "Polýbios"; c. 200  – c. 118  BC) was a Greek historian of the Hellenistic period noted for his work, "The Histories", which covered the period of 264–146 BC in detail. The work describes the rise of the Roman Republic to the status of dominance in the ancient Mediterranean world and included his eyewitness account of the Sack of Carthage in 146 BC. Polybius is important for his analysis of the mixed constitution or the separation of powers in government, which was influential on Montesquieu's "The Spirit of the Laws" and the framers of the United States Constitution.