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".
Polyaenus Polyaenus or Polyenus ( ; see ae (æ) vs. e; Greek: Πoλύαινoς , "Polyainos", "much-praised") was a 2nd-century Macedonian author, known best for his "Stratagems in War" (in Greek, Στρατηγήματα), which has been preserved. The "Suda" calls him a rhetorician, and Polyaenus himself writes that he was accustomed to plead causes before the emperor. Polyaenus dedicated "Stratagems in War" to the two emperors Marcus Aurelius (161–180 CE) and Verus (161–169 CE), while they were engaged in the Parthian war (162–165 CE), about 163 CE, at which time he was too old to accompany them in their campaigns.