Even on a tight schedule, Barcelona Cathedral (La Seu) earns the hours.
Allow 45 min–1 hr.
Lead with the quirks, because the Gothic shell is one of many in the old town. The serene cloister keeps thirteen white geese — said to mark Saint Eulàlia's age at her martyrdom — honking among palms and a fountain, a genuinely odd, only-here detail. And there's the mistaken-identity trap: a steady stream of visitors arrives expecting Gaudí, realises this is the 13th–15th-century La Seu (its showy main facade actually a neo-Gothic skin finished in 1913), and leaves faintly let down. Worth it for the geese, the rooftop lift and the cloister calm; underwhelming if you wanted the Sagrada and wandered in here by mistake.