“18 Centuries...”
Damn, almost TWO thousand years...
“The amount of construction done by the Roman Empire gets a little more stunning every year”
They had some SERIOUS engineering skills, for sure.
The Limes Arabicus in the Middle East stretched 1500 km, was built mostly to control the route of trade caravans, but also to prevent free movement of various ne'er do wells. It was reinforced with forts late in the main imperial era, but it was maintained by the Byzantines until the 7th c.