Some parts of London are astonishing.
A few years ago I took in a soccer match at Crystal Palace FC’s Selhurst Park stadium in the south London borough of Croydon.
I took the train south from Victoria Station (near Buckingham Palace), got into a nice conversation with a couple of Crystal Palace fans, who showed me the best way to get to the stadium. We got off at a station called Thornton Heath, and walked probably one-half mile to the stadium. The street ran through a Pakistani moslem business district; it was well and truly like being in Karachi. Never felt unsafe; but it was totally outside anything I had ever experienced before.
Same thing happens in Brussels.