Thanks Nanda e Gary! I went there several times, this one was from my last visit. Living in Oporto now I'm expecting to go there many more times (I'm still not happy with the results). It is indeed a difficult place to photograph!
I know this bookshop well, I once shot a whole roll of film in this place and not one of the exposures came out to my satisfaction. This image really shows the store at its best, great job. Regards, Gary