Yet if your trip doesn't happen to fall on a Sunday, no worries! Madrid has tons of other eclectic shops to browse your way through. From books and collectibles to vintage clothing and retro finds, this city truly has it all.
One bookstore in particular to check out is Panta Rhei. This shop has an amazing selection of graphic design and illustration books and carries options from both large and small independent publishers. Plus, the staff is extremely friendly and helpful.