Paris, Barcelona, Rome (maybe Munich too): You'd have to learn French, Spanish or Italian in order to live a normal life there. In Amsterdam, all the locals speak English, so it's pretty easy to stay here for several years without having to learn Dutch. I have several foreign friends who've been living here in Amsterdam for years without having learnt Dutch. Of course it's always better to know the local language wherever you live, but in Amsterdam you really don't have to.