I feel that there is something missing. "Travelling in Europe", "travelling over Europe", "travelling aroung Europe" sounds more natural to me. I think "Travelling Europe" is gramatically incorrect and doesn't sound right.
The main answer here is "travelling around Europe". "Travelling Europe" is also accepted, because this verb does in fact not need a preposition. There is plenty of evidence for that in various internet corpora.
The verb "interesować się" takes the Instrumental case for the thing that you find interesting. We could probably try to find out some reasoning behind it, but perhaps it's just easier to remember that it works like that.