One day
Start with a walk along the La Concha promenade and up Monte Urgull for the harbour view, then explore the Parte Vieja — the Plaza de la Constitución, the churches, the harbour. Graze a pintxos lunch bar to bar, swim or sunbathe on La Concha in the afternoon, and ride the funicular up Monte Igueldo for sunset over the bay before a long pintxos crawl back in the old town.