The penthouse was amazing ! Penthouse Prison offers you a perfect immersion as an inmate, with prison cells as bedrooms. As a guest, you have access to a bathroom with a toilet seat and a sink - beware that it is a prison type toilet seat so it might be a strange feeling for the first couple of times -, a bathroom with a shower and a sink - this one is slightly hard to use (still prison like shower) but you'll learn the technique pretty fast-, a small living room in a prison cell, a kitchen (not a prison cell) which contains a fridge (no freezer though), a dishwasher and furniture, keep in mind there is a single stove but no oven/microwave. Finally you have a beautiful view on Rotterdam with a huge terrace that you share with the people that work on the levels under the B&B (you'll live on the 4th floor, don't do too much noise, people are working beneath you!)
I'll put a 9.5/10 rating for this B&B, nearly 10/10 except the toilet seat was not really clean, but it did a beautiful job. I love this Airbnb and will probably come again !