The flat was very well located in a central area of Lisbon, walking distance from many of the sights. It was very clean and easy to check in as it’s a door code system so no need to wait around for anybody to let you in.
It is up quite a large hill though (as is most of Lisbon) so you may want to get a taxi as close as you can if you have heavy bags. Julia provides good instructions on how to get there by taxi.