"Trajan's Wall" (upper)
Not much known here but the length of 126km and that it is built not as high as the "lower" Trajan's Wall.
I indicated by a line about where it is to be looked for (reaching from the Pruth to the Dnister River.
chinoook's 1st law: Structural weak walls tend to show double structures.
chinoook's 2nd law: Walls are rather built next to older walls than to rebuild them. Newer walls avoid older walls rather than to replace them.
chinoook's 3rd law: Similar problems lead to similar solutions.
The most dangerous worldview is the worldview of people, who have not viewed the world. (Alexander von Humboldt (1769-1859), German naturalist and explorer)