A hidden gem
I never really heard of a lot of people going to Rotterdam, but I met a dutch guy in Prague who lived there and recommended it to me. Since my trip was kinda unplanned, I decided to make it happen and I'm super happy that I did! I would easily recommend Rotterdam over Amsterdam. It's a very unique port city with a lot of cool new architecture and you aren't running into tourists who just wanna get screwed up at every corner like in Amsterdam.
Insider Tip:Just spending some time walking around and seeing all the cool architecture can consume a lot of time. Also, since Rotterdam is the world's biggest port city, I would recommend the Dutch Maritime Museum. I'm not much of a museum person, but I really enjoyed this one.