Marta's apartment was a very lovely, remodeled apartment in the heart of Porto (city center) very conveniently located near Sao Bento station, Livraria Lello, Clerigo's, surrounded by amazing restaurants (natas!), and a short walk to a lot more attraction in Porto. Unfortunately, there's a very large construction project in between Sao Bento and the apartment currently, but luckily you cannot hear it from the apartment, you just need to walk around it.
The apartment itself is located on the second story (with elevator!) and nice spacious bathrooms and bedrooms which can get VERY dark if you want it to - which is great. As good as the apartment and it's amenities are, be aware that if you're traveling with kids under 3, there are steep staircases and enormous spacing through the upstairs' metal railing. Everything else was perfect, but we nearly had a heart attack any time our 18 month old would run around upstairs. So much in fact, that we had to move furniture around to try and mitigate any disasters.
Marta is a great host and went out of her way for anything we possibly could need. Superhost indeed!