Three days in Barcelona is enough to settle into its rhythm rather than race through it — one grand sight each morning, then long afternoons for wandering, coffee, and shopping streets. This route moves from the medieval lanes of the old city to Gaudi's architecture and finishes on the green hill of Montjuic.
Begin the morning at the Barcelona Cathedral (La Seu), then let the rest of the day unspool through the tangled lanes of the Gothic Quarter (Barri Gotic) — there is no better city for aimless wandering. Duck into the hushed Basilica de Santa Maria del Pi and pause in the square outside, where street musicians and small terraces make an easy spot for a mid-morning coffee. Walk past the Palau de la Generalitat and a stretch of the old Roman Walls before crossing into El Born for lunch. Spend the afternoon browsing the boutiques and workshops along Born's narrow streets, then step into the soaring Basilica de Santa Maria del Mar as the evening light comes through its windows. Round out the day with a visit to the Museu Picasso if the pace allows, or simply linger over a glass of wine at one of the small squares nearby.
Devote the morning to Sagrada Familia, booking tickets in advance and giving yourself a couple of unhurried hours inside — this is the one sight worth building the whole day around. Afterward, take a taxi or metro down to Passeig de Gracia and slow right down: this is Barcelona's grand boulevard, lined with flagship shops and two more Gaudi landmarks to admire from the pavement, Casa Batllo and Casa Mila (La Pedrera). Break for a long lunch on a shaded terrace, then spend the afternoon drifting between the boulevard's shops and side streets. In the early evening, walk over to see the ornate facade of the Palau de la Musica Catalana, and if a concert happens to be on, it is worth staying for.
Spend the morning on Montjuic, the green hill overlooking the harbor, starting with the collections of the MNAC (National Art Museum of Catalonia) and its sweeping terrace view back over the city. From there, an easy walk through gardens leads to the Fundacio Joan Miro, bright and airy inside, with a rooftop terrace worth the extra few minutes. Take lunch at one of the hillside cafes before spending the afternoon simply wandering the surrounding gardens and viewpoints at an unhurried pace. For a change of scenery to close the trip, head across town in the late afternoon to Park Guell, where mosaic terraces and shaded paths make a relaxed spot to watch the sun start to dip over the city.