[kuu]

I get your point, but that's not exactly the case. Madrid is built there not by coincidence, there are a lot of underground rivers that cross the region, but then the city was built on top of them.

See here: https://www-canaldeisabelsegunda-es.translate.goog/-/madrid-...

Original: https://www.canaldeisabelsegunda.es/-/madrid-la-ciudad-edifi...

And about ruins, they are, but they are also hidden: https://es.wikipedia.org/wiki/Muralla_cristiana_de_Madrid

:)

[noduerme]

Amazing! At Cava Baja 10 there's a remnant of the wall... and I never knew, I stay at the hotel across the street whenever I'm in Madrid and face that building.

Ironically, my comment about ruins, rivers, etc, I lifted from a sign in the lobby of that very hotel. And here they are sitting on top of it ;)