Things to Do in Barcelona

In short

Three full days is the right length for Barcelona; two days means cutting either Park Güell or the Gothic Quarter.
May and late September to October are the best months — warm, open, and cheaper than the July–August peak.
Sagrada Família, Park Güell, Casa Batlló and La Pedrera all use timed entry and sell out weeks ahead in summer.
Stay in Eixample on a first visit; El Born if you want to walk to dinner.

Three full days covers Barcelona properly: one for the Gaudí buildings, one for the old city and the waterfront, one loose day for Montjuïc or a trip out to Montserrat. Two days works but means skipping either Park Güell or the Gothic Quarter. Go in May or from late September to October — July and August are hot, crowded, and the most expensive time to sleep here.

Book the Gaudí buildings before anything else

This is the one part of a Barcelona trip that punishes improvisation. Four Gaudí sites use timed entry, and in summer the popular slots go weeks ahead. Turning up without a slot usually means not getting in at all.

Sagrada Família — the basilica, still unfinished; book the earliest slot for the east-facing morning light.
Park Güell — a terraced hillside above the city; the free area is large, the paid Monumental Zone is the mosaic part.
Casa Batlló — the sea-themed house on Passeig de Gràcia, the most crowded of the four.
La Pedrera (Casa Milà) — five minutes further up the same street, known for its rooftop chimneys.

If you only do two, make them the Sagrada Família and Park Güell. They are the two that look nothing like the photographs — the basilica because of what the light does inside it, the park because it is a hillside with a view rather than the single mosaic bench everyone photographs.

The old city is for walking, not for a list

The Gothic Quarter, El Born and El Raval sit next to each other between Plaça de Catalunya and the sea. They reward wandering more than ticking off sights, but four things are worth aiming at:

Barcelona Cathedral — the Gothic one in the Barri Gòtic, not the Sagrada Família.
Santa Maria del Mar — a plainer, better-proportioned church in El Born.
Picasso Museum — holds his early work; the famous later paintings are elsewhere.
Mercat de Santa Caterina — the market locals use, a few streets from the tourist-priced Boqueria.

La Rambla runs through the middle of it and is worth walking once, briefly. It is the most pickpocketed street in the city and the food on it is priced for people who will not come back. Turn off it early.

Montjuïc is the half-day most people cut, and should not

The hill south of the centre holds the Joan Miró Foundation, the Montjuïc castle, and the best free view of the city. A cable car runs up from the harbour and a funicular from Paral·lel metro station.

Day trips worth the train fare

Day trips from Barcelona
Where	Travel time, one way	Best for
Montserrat	~1 hour + rack railway or cable car	Mountain monastery on a serrated rock massif
Girona	40 minutes by high-speed train	A small walled city with an intact Jewish quarter
Sitges	35 minutes by local train	Beach town; the easiest of the three on a half day
Tarragona	~1 hour	Roman amphitheatre above the sea

Montserrat is the one to pick if you only do one, and it is the one that needs a full day rather than an afternoon.

The terrace at Park Güell, BarcelonaJulian Lupyan · CC0

Common questions

Is 2 days enough for Barcelona?

It is enough for either the Gaudí buildings or the old city, not both at a reasonable pace. Three days is the point where the trip stops feeling rushed.

What is the cheapest month to visit Barcelona?

January and February. They are also the coldest and wettest, and some beach-side places close. November is the better compromise.

Do I need to book the Sagrada Família in advance?

Yes. Entry is by timed slot and summer slots sell out weeks ahead. It is the single most common way a Barcelona trip goes wrong.

Is Barcelona walkable?

The old city and Eixample are, and they hold most of what visitors come for. Park Güell, Montjuïc and the beach are far enough apart to want the metro.