Thanks to richard, we can enter the house very easily. There was somewhat many stairs, but after we went up the stairs, it does not matter.
We had a great time in that house and there was useful information about the city(rotterdam). The location of the house was good and in the middle of the street between the house and the central station, there were beautiful lake ! And there was big supermarket near house, so u can buy everything you need. Richard came to house to explain how we can enjoy the city. It was great to meet him and thank u !