Our stay in Montebelo Lisbon: checked in Wednesday-checked out Friday morning. Our flight landed around 11:30AM on Wednesday and they arranged transportation from the airport and thankfully were able to check us in early (normal check in is 2PM and they checked us in at 12:30PM). We had requested a room on a higher floor based on other reviewers mentioning the loud street noise and they graciously gave us a room on the fifth floor (there are six levels). As soon as we walked into the room we were greeted with a strange smell, however, we thought maybe opening some windows would help. We opened the windows and went on our adventure around beautiful Lisbon. When we got back to the room in the afternoon to get ready for dinner the smell was unfortunately still there and that is when we notified the front desk, however, they said they would address it in the morning (the front desk workers leave at 6PM and I believe this was around 7PM). In the morning, we spoke to the front desk and they mentioned they would look into the smell during the day, however, when we arrived back to the room at 4PM the front desk said maintenance would be there within 30 minutes. At around 5:30PM, maintenance still wasn't there and we went down to the front desk when they told us maintenance wouldn't be there until the morning (the day we check out). They thankfully refunded us for one night, however, it was unfortunate we had to endure the smell during both nights of our stay. I believe it was a sour sewage smell coming from the kitchen somewhere. We tried looking all over the place for what it could be, however, it is still a mystery. Other than the issue with this smell, the apartment was great and in a very central location. The front desk was also helpful with recommendations on where to get wine, breakfast, etc.