Sergio was very nice to let us have a very late check-in. His place is situated in Mouraria, in the older part of the city. It is a steep slope up to his house; luckily our car was small enough to go up. Parking is directly outside the house.
The flat is on the first floor and it has an interesting design. Although it isn't very big, you have everything you need - it is very well equipped. Overall, I would recommend Sergio's place to anyone coming to Lisbon. It's near the castle and a good place to start if you want to explore the Alfama area.