We had a fantastic stay at Marc's apartment and would recommend this place very highly. It's in a really great location being so close to everything. It's just a short walk to the nearest underground station or into the Born or Gothic Quarters or the main part of the city. There are plenty of bars, cafes and shops around the area if you don't want to move too far. It's also just far enough away from the hustle and bustle that it's very peaceful at night.
The apartment itself is just beautiful. I'd be very happy to live here! It's been renovated by someone with a very good eye for design and looks great but also very comfortable to lounge about in. We loved lazing about with the windows open fully and listening to the sound of Barcelona filtering in. It's also well equipped and has everything you need, including all kitchen utensils and appliances.
Marc was a very friendly and helpful host. He was very responsive to my messages before our visit and met us on site to check us in and show us around. It looks like Marc might have other apartments in the same building so if this one isn't free take a look at his other City Centre ones. This was definitely one of our favorite AirBnB stays!