There's some of these in Paris along the historic route of the abandoned "Petite Ceinture" railway. Here's one example where buildings have been built in the w

There's some of these in Paris along the historic route of the abandoned "Petite Ceinture" railway. Here's one example where buildings have been built in the way: https://www.google.ca/maps/place/Petite+Ceinture+du+12%C3%A8me/@48.8211799,2.3492272,244m/data=!3m1!1e3!4m5!3m4!1s0x47e673868200a2c1:0xedd2a9a45252513a!8m2!3d48.8329998!4d2.3993023 https://www.google.ca/maps/place/Petite+Ceinture+du+12%C3%A8...