Rotterdamn is beautiful but most of my time there got rained out. I stayed in a very cool Art exhibit AirBnB. I walked around alot taking in history. Through out the city as you walk around keep your eyes open. In front of many houses there are gold bricks or many gold bricks. These indicate the house's where Jews were taken from by the Nazi's during WWII.
A fun activity to do is to go visit Markthal. After a visit to the Markthal which is an amazing market hall/ office and residence complex which has graphicly mapped walls with some of the most stunning projected graphics you will see.
P.S. Rotterdamn also has Coffee Shops (for the pots ;))