Nice stay in Porto, immediately next to the Sé and 5min walking from ponte de Dom Luís. The self check-in is a real plus if you are arriving late at night. The appartment is small and you sleep on a sofa-bed, but it's comfortable and has everything you need. From that point highly recommended.
Just a note, the Uber driver who dropped us off told us to stick to the main road at night and avoid the small streets behind and around the building because it's not safe. We follwed his advice and everything was fine (at day it's ok to walk the streets), even as two women we did not feel unsafe, but it would be nice if the host could have shared that information with us as well, now I was lucky that my friend speaks Portuguese and understood the Uber driver.