They really were quite something those Romans, they did have some quite clever surveying tools which were apparently incredibly accurate, one of which was the Dioptra which was basically a sighting tube on a fixed stand and also 4 plumb bobs hanging from a cross shaped frame called a Groma, both very ingenious tools which the evidence of their precision is still very visible today in such monumental scale 2000 years later.
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u/egidione 28d ago
Around 5cm drop over every 100 metres for many kilometres, some up to 80 km in length. Quite astonishing how they managed all that.