This airbnb is ideally located close to the Rossio metro station, and just below the castle. It's in a little foot street inaccessible by cars, so reasonably peaceful, with just some moderate restaurant noise at night (no discos).
The apartment is spartan, and in need of some very minor maintenance (eg a broken fridge door handle), but is otherwise fully equipped and comfortable.
There are two bedrooms. The master bedroom has a window, and the other room with two beds has just an internal window. The beds are firm, so you will sleep well.
I did not meet the hosts, but the neighbour handed off the keys and was very helpful.