Casa Milà was commissioned in 1905–06 by businessman Pere Milà and his wife, Roser Segimon, after they acquired a prominent corner on Barcelona’s Passeig de Gràcia. The expanding Eixample had become a setting where wealthy families advertised status through architecture. They hired Antoni Gaudí, already known for highly individual buildings, to create a residence for themselves with rentable apartments above and around it. Plans were submitted in February 1906, and construction continued until 1912. It was Gaudí’s last major secular building before he concentrated on the Sagrada Família.

Gaudí treated the apartment block as a structural and spatial experiment. A self-supporting stone façade wrapped around two internal courtyards, while columns and metal beams reduced dependence on load-bearing interior walls. This allowed flexible apartment plans and large openings for light and ventilation. Ramps served an underground garage, an unusually forward-looking response to automobiles. On the roof, stair towers, ventilation shafts, and chimneys became sculptural forms. The undulating limestone exterior and twisting iron balconies quickly inspired the nickname La Pedrera, meaning the quarry.

The design caused conflict. Neighbors and satirical magazines mocked the building, while municipal officials objected to elements that exceeded regulations. The Milàs disputed costs and aspects of Gaudí’s religious symbolism; a proposed monumental image of the Virgin was never installed. Gaudí eventually went to court over unpaid professional fees and won. Despite those tensions, he certified the building complete on 31 October 1912, ready for tenants. Its mixed reception reflected a city negotiating between conventional respectability, technological modernization, and the radical language of Catalan Modernisme.

Roser Segimon continued to own and inhabit the building after Pere Milà’s death in 1940. Alterations subdivided spaces, modified decoration, and accommodated shops, offices, and apartments. During the Spanish Civil War, political organizations occupied parts of the property, and the building passed through the disruptions of revolution and dictatorship. It was sold in 1946, after which rooftop and interior changes sometimes disregarded Gaudí’s design. By the later twentieth century, however, architectural scholarship and heritage campaigns had transformed the once-ridiculed house into a national and international landmark.

UNESCO included Casa Milà in its 1984 World Heritage designation for works of Antoni Gaudí. A financial institution acquired the property in 1986 and undertook major restoration, reopening significant areas for cultural use and public visits. The building still contains residential and commercial functions, preserving the tension between lived apartment house and museum. Its history is not simply the triumph of a misunderstood genius. It also records patronage, labor, legal dispute, urban regulation, civil war, property change, restoration, and the creation of Barcelona’s modern heritage economy.

Conservation also revealed how inseparable the celebrated façade is from the less visible systems behind it. Courtyards distribute air and daylight, attic arches carry the roof terrace, and structural independence allowed residents to alter rooms. These features made Casa Milà influential among later architects. They also remind visitors that Gaudí designed an income-producing urban building whose innovations were meant to support domestic routines, tenants, servants, vehicles, and changing commercial uses over time.