Hladova Zed, Picture 2, Prague, CZ, 2006

For a city wall that was, at least allegedly, never intended for use, the Hladova Zed is very well fortified with fortresses for troops, ammunition, weapons, and so on, especially towards the top of Petrin Hill. Most of these buildings are unoccupied, though, without even any ruins or museums inside them, so I don't know whether they were ever completed originally.