At the time, it was controversial because of its undulating stone facade, twisting wrought iron balconies, and design by Josep Maria Jujol.

Several structural innovations include a self-supporting stone façade, and a free-plan floor, underground garage and the spectacular terrace on the roof.

Since 2013 it has been the headquarters of the Fundació Catalunya La Pedrera, which manages visits to the building,[1] exhibitions and other cultural and educational activities at Casa Milà.

Roser Segimón was the wealthy widow of Josep Guardiola, an Indiano or Americano, or former colonist returned from the Americas, who had made his fortune with a coffee plantation in Guatemala.

On February 2, 1906, the project was presented to the Barcelona City Council and the works began, demolishing the pre-existing building instead of reforming it, as in the case of the Casa Batlló.

[10] The building was completed in December 1910 and the owner asked Gaudí to make a certificate to inhabit the main floor, which the City Council authorized in October 1911, and the couple moved in.

On October 31, 1912, Gaudí issued the certificate stating that, in accordance with his plans and his direction, the work had been completed and the whole house was ready to be rented.

The local government ordered the demolition of elements that exceeded the height standard for the city, and fined the Milàs for many infractions of building codes.

Segimon sold the property in 1946 for 18 million pesetas to Josep Ballvé i Pellisé, known for his department stores on Ronda de Sant Antoni [ca], in partnership with the family of Pío Rubert Laporta.

In 1953, they commissioned Francisco Juan Barba Corsini [es] to convert 13 rubbish-filled attic laundry rooms to street-facing apartments, leaving a communal hallway on the side facing the courtyards.

The attic housed the laundry and drying areas, forming an insulating space for the building and simultaneously determining the levels of the roof.

All of these elements, constructed out of brick covered with lime, broken marble, or glass have a specific architectural function but are also real sculptures integrated into the building.

The apartments feature plastered ceilings with dynamic reliefs, handcrafted wooden doors, windows, and furniture, as well as hydraulic tiles and various ornamental elements.

The stairways were intended as service entries, with the main access to the apartments by elevator except for the noble floor, where Gaudí added a prominent interior staircase.

This construction system allows, on one hand, large openings in the facade which give light to the homes, and on the other, free structuring of the different levels, so that internal walls can be added and demolished without affecting the stability of the building.

The blocks were cut to follow the plot of the projection of the model, then raised to their location and adjusted to align in a continuous curve to the pieces around them.

The centerpiece was built in a shipyard by Josep Maria Carandell who copied a steering wheel, interpreting Gaudí's intent as to represent the helm of the ship of life.

Gaudí agreed to remove a pillar on the ramp that led into the garage so that Felix, who was establishing sales and factory in Parets del Vallès, could go to both places with his car from La Pedrera.

The wax was designed in gray by John Bertrand under the supervision of Gaudí who "touched up with their own fingers," in the words of the manufacturer Josep Bay.

[25] Like in Casa Batlló, Gaudí shows the application of the catenary arch as a support structure for the roof, a form which he had already used shortly after graduating in the wood frameworks of Mataró's cooperative known as "L'Obrera Mataronense."

The roof resembles both the ribs of a huge animal and a palm, giving the roof-deck a very unconventional shape similar to a landscape of hills and valleys.

The work of Gaudí on the rooftop of La Pedrera brought his experience at Palau Güell together with solutions that were clearly more innovative – this time creating shapes and volumes with more body, more prominence, and less polychromasia.

[27] On the rooftop there are six skylights/staircase exits (four of which were covered with broken pottery and some that ended in a double cross typical of Gaudí), twenty-eight chimneys in several groupings, two half-hidden vents whose function is to renew the air in the building, and four domes that discharged to the facade.

One of the chimneys was topped with glass pieces – it was said that Gaudí did that the day after the inauguration of the building, taking advantage of the empty bottles from the party.

This was part of the concept artwork itself integral to modernism in which the architect assumed responsibility for global issues such as the structure and the facade, as well as every detail of the decor, designing furniture and accessories such as lamps, planters, floors or ceilings.

Some remain in private collections, including a curtain made of oak 4 m. long by 1.96 m. high in the Museum of Catalan Modernism; and a chair and desktop of Milà.

[citation needed] Gaudí carved oak doors similar to what he had done for the Casa y Bardes, but these were only included on two floors as when Segimon discovered the price, she decided there would be no more at that quality.

Joan Matamala thought that the model could have been St. Miquel del Fai, while the sculptor Vicente Vilarubias believed it was inspired by the cliffs Torrent Pareis in Menorca.

[16] Homeowners in Passeig de Gracia became angry with Milà and ceased to greet him, arguing that the weird building by Gaudí would lower the price of land in the area.

Again on August 17, 1908, more problems occurred when the building surpassed the predicted height and borders of its construction site by 4,000 square metres (43,000 sq ft).