An older, maybe more impressive example (just because of the age of it, or maybe because of my interest in it) is the hydrological systems built in Rome itself.

An older, maybe more impressive example (just because of the age of it, or maybe because of my interest in it) is the hydrological systems built in Rome itself. I'll have to dig out the book I read this out of, but there is some evidence that a large part of what was the Forum was man made and made of infill, with the Cloaca Maxima [1] (which is still around and working) built to attempt to manage flooding from the Tiber. The Tiber is a silt heavy river, and the sewers requried pretty constant maintenance. When the Cloaca Maxima was blocked with silt sometime int he early Middle Ages, the Forum began flooding again and ended up buried by modern times under a significant amount of soil. See pictures [2] and [3] of the same structure from (a painting) in the 1800s and modern day after the excavation. It really shows the power of nature and the success of engineering. [1] https://en.wikipedia.org/wiki/Cloaca_Maxima https://en.wikipedia.org/wiki/Cloaca_Maxima [2] Before: https://upload.wikimedia.org/wikipedia/commons/a/a0/Canaletto_Arch_of_Septimius_Severus.jpg https://upload.wikimedia.org/wikipedia/commons/a/a0/Canalett... [3] https://upload.wikimedia.org/wikipedia/commons/thumb/3/38/Rome-ForumRomain-ArcheSeptime.jpg/1280px-Rome-ForumRomain-ArcheSeptime.jpg https://upload.wikimedia.org/wikipedia/commons/thumb/3/38/Ro...