Mário's apartment was the best possible choice for staying in Porto a couple of days! It is close to the city center by foot and has a metro station only 1 min walk away. It is a cozy ,very clean and well taken care appartment.
Mario and his wife are both very nice and were always available for helping out their guests. They made a map of Porto with the directions for all main attractions and soon will have a smartphone app to help their guests!
I recommend Mario's apartment for a perfect stay in Porto!