Antoni Gaudí’s masterpiece — book tickets in advance for a morning slot; typical opening ~9:00–19:00 but times change seasonally, so confirm before visiting.
Take the cable car up to the castle for panoramic city and harbor views; cable car and castle generally open from mid-morning to early evening, confirm seasonal hours.
Open-air crafts village (Poble Espanyol) and modern architecture highlight (Mies Pavilion) on Montjuïc — both usually open until late afternoon/evening.
Visit the Basilica, Black Madonna and museum; the Abbey area is open daily but museum and special exhibitions have separate hours — arrive early to avoid crowds.
Stunning Modernisme concert hall with guided tours available most days (typically mid-morning to mid-afternoon) — book a tour to see the interior detail.
Optional 2-hour catamaran or sailing trip from the harbour (many depart afternoons) or relaxed beach time on Barceloneta; check operators for exact departure times.
Allow 45–75 minutes to Barcelona–El Prat depending on traffic; Aerobus from Plaça Catalunya runs frequently (typical fare ~EUR6.75) or take a taxi for convenience.