Puerta del Sol
Calle del Postigo de San Martin, 8, Puerta del Sol
This handsome bookshop occupies a stately renovated townhouse, so the architecture is an elegant (if fittingly mismatched) mix of Baroque arches and streamlined modern walls and skylights that span three levels in addition to a basement-level event space. The adorable children's section, for example, occupies the former chapel and boasts a ceiling complete with gold-trimmed domes painted with images of angels and cherubs. The entire shop is always buzzing thanks to a cozy cafe, a rooftop bar (on Thursdays you're likely to find a band performing live music), and a packed schedule of events that brings in writers and lecturers from all over Europe.