Barcelona in one day
One day forces a choice, and this is the selection that works: the Sagrada Família in morning light, the old town digested on foot and the sea as dessert. Start genuinely early.
Morning: Eixample and Sagrada Família
Sagrada Família at nine with a booked slot, a walk down Passeig de Gràcia past the block of discord, and coffee at any neighborhood bar's counter. All in a straight metro line.
Afternoon: Gothic and Born
From the cathedral to plaça del Rei, Santa Maria del Mar and the Picasso only if there's truly time. Set-lunch menu in El Born or the Santa Caterina market, away from La Rambla's door.
Close: sea and sunset
Walk the promenade to Barceloneta in the last hours: sunset over the sea and the hotel Vela make the final chapter. Tapas dinner in the neighborhood and sleep with the city won.