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".
Aeneas Tacticus Aeneas Tacticus (Greek: Αἰνείας ὁ Τακτικός ; fl. 4th century BC) was one of the earliest Greek writers on the art of war and is credited as the first author to provide a complete guide to securing military communications. Polybius described his design for a hydraulic semaphore system.