Final answer:
Visitors from beyond the frontier were astonished by the arches and the aqueducts. Aqueducts were structures used in ancient civilizations, including the Roman Empire, to transport water over long distances, and were a testament to their engineering and technological prowess.
Step-by-step explanation:
Visitors from beyond the frontier were astonished by the arches and the aqueducts. Aqueducts were structures used in ancient civilizations, including the Roman Empire, to transport water over long distances. They were often built with arches to support the flow of the water. The aqueducts were a testament to the engineering and technological prowess of ancient civilizations.
Learn more about Aqueducts in ancient civilizations