Lourdes' apartment is just a block off the main drag in the tourist section of town. Next door to the apartment are several good restaurants and bars. The place is immaculate, well decorated and she has provided just about everything you will need for a one-week stay, including clothes washer and dishwasher. It has a little patio for coffee in the morning and it is on the second level, so there is only one flight of stairs. It can't be more than a five minute walk to Rossio Square, and only one minute walk to Monumento aos Restauradores / Avenida da Liberdade.
Other apartments in the building appear to be rented to tourists as well, but all seems well behaved and friendly. Lourdes is very responsive by email (through AirBnB). My wife and I were in town on business and pleasure, and we would go out of our way to return to this place.