Safe luggage lockers in Lisbon?

I'm standing at a City Lockers left luggage facility in Lisbon.

Hours: 9am - 7pm, daily
Prices: €4.5 -€7.5 per item per day

Address: their blue sign is near Rua Garrett #10 (a big shopping street not far from Rossio station)

ETA: the gal at the desk wrote down it's near address #10, but I can see the sign and stairs are between #27 and #31. If you look waaaaaaay up, the entrance to the stairs themselves are under an archway with the #29.

Whatever the address, go up the concrete stairs and inside the concrete courtyard, on your left will be the staffed desk.

Manager: Humberto Teixeira
Humberto.teixeira@citylockers.pt
Www.citylockers.pt

Thank you. I saw their info on the internet, but was not sure where in the airport. It sounds like a well lit area.

Just to clarify, it's in the center of Lisbon, not at the airport. It's on a street with lots of stores and close to a big Galleria type mall. The street is very busy with shoppers and foot traffic during the daytime and early evening. The stairs and up to the courtyard are not - there is nothing else up there.

There was a lone gal staffing the place when I went there. I felt perfectly comfortable going up during their business hours. I'm not sure I'd wander up into the courtyard in the middle of the night.

Thank you.