The apartment is perfect, and Arthur & Diogo are the most friendly and helpful hosts you could ever meet.
Our flight landed quite early (10 AM). Fortunately, Arthur promised we could leave our luggage to the apartment before check-in. We took the metro to Martim Moniz station, which is near the apartment. We met Arthut at nearby cafe, and walked to the apartment. We left our luggage and went to see the neighbourhood while the Arthur and his mother cleaned the apartment after the previous guest.
When we returned, we noted that the apartment was roomy, light, and shining clean. Everything was perfect: bedclothes, towels, kitchen equipment, a bottle of white wine in the fridge...Arthur spent some 30 minutes showing us how things work, and telling us about Lisbon and the places and restaurants we should visit.
We spent 4 nights, and found absolutely nothing to complain about. Arthur & Diogo were all the time available by Whatsapp, if we needed to ask something. We had a late flight (11 PM) back. Again, we were allowed to leave our luggage at the apartment after check-out time (until 4 PM) , so we we free to walk around the city. Thank you Arthur & Diogo! Your place gets an absolute recommendation from us!