This apartment is amazing! The location is one of the best I’ve ever stayed in for an Airbnb. You are within the castle walls (not the ticketed area, but the old streets just beyond) and we woke up each morning to the castle peacocks strolling down our street. It is on top of one of the seven hills in Lisbon so if mobility is an issue for you, something to consider. However, there is a bus that runs often just two short blocks away and there is also a series of elevators to help you out.
Another thing to note, the bathroom is not very private for visual and sound reasons. As husband and wife, we were very ok with it. If I had been there with a new boyfriend, I might have felt a bit strange (but probably would have gotten over it because of the previously mentioned wonderful stuff!)