Casa Batlló or La Pedrera: one is a refit, the other is a building

They are two hundred metres apart on the same pavement. Most people choose between them on the strength of a photograph, which is the one criterion that does not distinguish them, because both façades are free.

Here is the difference that actually decides it.

One of them is a conversion

The house at Passeig de Gràcia 43 was not built by Gaudí. It went up in 1877, and Casa Batlló’s own history names the architect: Emili Sala Cortés, one of Gaudí’s own architecture professors.

Josep Batlló, a textile industrialist with several factories, bought it in 1903. His first instruction was to knock it down. Gaudí talked him out of it, and what happened between 1904 and 1906 was a renovation: a new front, the partitions redistributed, the lightwell enlarged.

So the building people queue for is Gaudí working over his teacher’s plan, on a site he did not choose, inside a volume he inherited. That is not a criticism. It is the most interesting thing about it, and nobody says it at the door.

The other one is exempt from the rules

Casa Milà was designed and built from 1906 to 1912, and it is Gaudí’s last civil work. He filed the plans with the council on 2 February 1906, and certified the building finished on 31 October 1912, declaring the whole house ready to be rented.

In between, one sentence from La Pedrera’s own history that we think is the single best fact about either building:

In 1909, the Eixample Commission certified that the building was monumental in character and did not have to comply strictly with municipal ordinances.

The city looked at a block of rental flats, decided it was a monument, and let it out of its own rulebook while it was still going up. Whatever you think of the stone, that is what confidence looks like on paper.

What you are buying, in each case

Casa Batlló’s argument is light. There was one lightwell; Gaudí made it two, so that daylight could reach every room. He tiled them blue, darker at the top and lighter at the bottom, so that the shaft would read as one even tone from any floor. He made the upper windows smaller and the lower ones larger, for the same reason. There are wooden slats in the bottom of each window to trim the ventilation.

That is a piece of engineering disguised as a colour scheme, and once you have seen it you cannot unsee it. The lift is still the original wooden cabin, still working. The attic runs on sixty catenary arches. The roof has four sets of chimneys shaped so the air cannot blow back down them.

La Pedrera’s argument is structure. The façade carries nothing: it is a non-load-bearing curtain wall, more than 6,000 stone blocks hung on the frame with metal fixings, in three different stones — Garraf limestone low down, larger pieces from Vilafranca del Penedès, Ulldecona limestone in some of the window frames. A wall with no job is free to do anything, which is why it waves.

Inside, he threw away the thing every Eixample rental block had: the main staircase. Tenants went up by lift or by the service stairs. Stone pillars and brick instead of load-bearing walls, so the flats could be laid out freely. A basement garage for carriages and motor cars, the first in a residential building — one early tenant’s Rolls-Royce obliged Gaudí to alter the entrance.

And the attic: 270 catenary arches, brick, light, standing on their own with no buttress, doubling as the building’s thermal chamber. Windows open in summer for the draught, shut in winter to hold the sun. Around it a walkway with four cupolas the house describes as shaped like Prussian helmets.

Sixty against two hundred and seventy

If you want one number to carry the whole comparison, that is it. Both attics are catenary. One is the attic of a converted house; the other is the roof structure of a building conceived from the pavement up.

Why that shape at all, and what a catenary is for, is the subject of its own page: why Gaudí’s buildings stand up.

The listings do not agree either, and it is worth knowing

Casa Milà, Park Güell and Palau Güell were declared World Heritage on 2 November 1984. Casa Batlló was not added until 2005, in the extension that also brought in Casa Vicens and the Colònia Güell crypt. Twenty-one years between the two houses on the same street, and if you were ranking them by institutional esteem rather than by Instagram, that gap is the ranking.

One more, smaller. Barcelona’s own heritage catalogue dates Casa Milà 1906-10. The building’s own final construction certificate is 31 October 1912. We have no way to reconcile those and we are not going to average them; we mention it because this site’s whole argument is that you should be able to check us, and when two official records disagree the honest thing is to show both.

So, which

Go into La Pedrera if you have one interior and you want to understand a Gaudí building. The roof and the attic do more for you than anything in the city, and it is the only one of the two where every decision was his.

Go into Casa Batlló if you are travelling with people who want to be delighted rather than instructed, or if the lightwell is the kind of thing that makes your day. It is the more theatrical visit, deliberately, and it is also the busier one.

Go into neither if your trip is short and already carries a basilica ticket. Both façades read completely from the pavement opposite, at any hour, for nothing, and the street they share also holds Casa Amatller by Puig i Cadafalch and Casa Lleó Morera by Domènech i Montaner — plus, on the same block and almost never named, Casa Mulleras by Enric Sagnier and Casa Josefina Bonet by Marcel·lí Coquillat. Their owners were competing for the city council’s architecture prizes. That argument is in modernisme beyond Gaudí, and it is free.

Two things to look at while you decide

Gaudí “never explained his work”, says the house that owns Casa Batlló, and “directed the façade work from the outside, without precise plans, as was customary for him”. So the dragon, the skulls, the carnival masks and the water lilies are all readings, and the building’s own pages label them as readings. What is on the façades and what the buildings themselves say it means is in the things people walk past.

The broken-ceramic surfaces on both roofs have a technique and a shopping list behind them, and one group of La Pedrera’s chimneys is clad in the bottoms of champagne bottles: trencadís, and what it is actually made of.

Who paid for each of these houses, and what they did for a living, is in who paid for each Gaudí building — the short version being that La Pedrera was not Pere Milà’s money. And the day that fits both of these in without ruining itself is Gaudí in one day.

If you would rather not go inside anything

Our Gaudí walk is ninety minutes on the pavement outside the Sagrada Família with an actor playing Antoni Gaudí, fifteen people, and no ticket office anywhere in it. It will not get you into either of these houses and it does not try to. It is the argument, out loud, in the street where it belongs.