Having travelled a bit when I was younger.
Belfast, Omagh and Tel Aviv were by far the worst in Europe.
Eastern Europe was always interesting and I’d certainly wouldn’t go walking around alone in the the likes of Riga, Minsk, Dnipro or Tallin.
Let’s be honest though, certain parts of most cities can be a bit rough. Birmingham, Nottingham, Manchester, Bradford, Liverpool and Glasgow all have areas which I’d rather not visit in a group, never mind alone.