Hi! We have a 24 hour layover in Barcelona! Would love to hear people's must sees! Thank you!
Here is a suggested itinerary by our host https://www.ricksteves.com/europe/spain/barcelona-itinerary
Barcelona in One Day
For a relaxing day, stroll the Ramblas, see the Sagrada Família, add the Picasso Museum if you're a fan, and have dinner in the trendy El Born district.
To fit in much more, try the following ambitious but doable plan. You'll have to rush through the big sights (cathedral, Picasso Museum, Sagrada Família), having just enough time to visit each one but not to linger.
9:00 From Plaça de Catalunya (with its handy tourist information office), peruse the Barri Gòtic neighborhood (follow my guidebooks' self-guided walk, also available as a free audio tour) and tour the Cathedral of Barcelona.
11:00 Circle back to Plaça de Catalunya and stroll Las Ramblas to the harborfront (ideally, following my guidebooks' self-guided "Ramblas Ramble").
12:30 Walk along the harborfront to El Born, grabbing a quick lunch.
14:00 Tour the Picasso Museum.
16:00 Hop a taxi or the Metro to the Sagrada Família.
18:00 Taxi, bus, or walk to Passeig de Gràcia in the Eixample to see the exteriors of Gaudí's La Pedrera (a.k.a. Casa Milà) and the Block of Discord. Stroll back down toward Plaça de Catalunya.
19:00 Wander back into the Barri Gòtic at prime paseo time. Enjoy an early tapas dinner along the way, or a restaurant dinner later in the Old City.