I loved my stay in Bilbao and in Fernando's apartment. It's located very much in the center of Bilbao, still it's a nice and quite neighborhood.
The old town can easily be reached by walking 5 to 10 minutes and also to the Guggenheim, even if it takes like 20 minutes to reach by foot, it's a nice walk along the river.
The room is spacious and with a big comfortable bed. Also you have a nice view over Bilbao's rooftops.
Fernando himself was extraordinarily inviting and helpful. Thanks for the interesting conversations even though my Spanish is quite bad ... haha.
I definitely recommend this place!!!