Not uncommon. Cities grew and the aqueducts just went director to their river, si they suck and paving them was a good excuse to get rid of the sanitation problems they had while expanding car infrastructure. Cities today know better and built aqueducts that didn’t dump everything to the river.

Pretty much, yes - the Stadsbuitengracht was a defensive moat originally, then they converted part of it into a motorway in the 70s.

In 1973 they replaced the canal with a road, since… cars go vroom vroom and need space, but this was reverted between 2010-2020.

no, they built a canal later