San Marino is a country made of nine "castles", and the one with the higher population is "Serravalle".
Actually, I got 118 without going near ANY of these cities.
if you exclude former capitals aswell you go quite a distance up.
I've only been to Sydney, Johannesburg and Gaborone.
Anyway, for Liechtenstein I have a reliable swiss source, claiming that Vaduz is the most important city (being the first named) of the transnational agglomeration of Vaduz-Buchs! Schaan it is only a part of it. It's in french, but really easy to understand. http://www.bfs.admin.ch/bfs/portal/fr/index/regionen/11/geo/analyse_regionen/05.html
If you ask for the biggest urban area in Germany, Ruhr Area should be the correct answer. Or Düsseldorf, if you want the answer to be a city.