I very nice little flat within the walls of the castle. We enjoyed our stay there. The flat is small so it might be a bit tight for more than 2 people. The hosts were excellent, responding very quickly to messages and checking in and out was very smooth. The flat is at the top of the highest hill in central Lisbon so it can be a bit of a slog up the hill at the end of a long day if the buses have stopped (after around 21.00) and the elevators are closed. There's a school nearby that can be a little noisy in the morning during the week. It's clean and comfortable flat though, and the views from the castle next door are excellent.