Some lady just unlocked our room with a master key, and after finding us, she ran away. Upon inquiry with the front desk, they said they know the women and would ask her to explain herself. She did come to our room again, said something in Portuguese, but she did not know English (and neither did the front desk person). We had no idea what she said - we asked if she was room service or manger, she just kept nodding. All we could understand is there are master keys. Knowing this, and without any sufficient explanations, we felt unsafe to stay at this hotel. Also, the breakfast food was old and smelled bad.
Though it is close to various museums and Luz station, and other staff members were friendly to us, we cannot recommend this place due to this incident.