Why are some places worth a sightseeing trip and others aren’t?

There’s nothing wrong with a vacation selfie - they also underline the fundamental question of which sights are worth seeing during a trip. — CHRISTIN KLOSE/dpa

Have you ever walked by a group of tourists while going about your day and wonder what they’re so fascinated by?

German tourism researcher Martin Lohmann’s job is to try to answer this question, and others, on what makes tourists tick.