La Pedrera (Catalan for 'The Quarry', so named for its cliff-like walls) is the colloquial name given to the 'Casa Milà', the building Antoni Gaudí designed for Rosario Segimon and Pere Milà. This important Barcelona landmark, found on the Eixample's Passeig de Gràcia, was completed between 1906 and 1910. La Pedrera is a limestone building with wrought-iron details, a combination of dramatic contrast. The many wrought-iron balconies were the design of Josep Maria Jujol, Gaudí's frequent collaborator. Each is different and was improvised in the forge. La Pedrera was once occupied as an apartment building. Two large curvilinear internal courtyards provide light to the central interior. A large staircase running alongside the courtyard leads to the former residence of Segimon and Milà. The rooftop, accessed by any of six staircases, is filled with large sculptures, some of which evoke designs used in nearby Casa Batlló and Park Güell. La Pedrera has six floors, then a two-level penthouse (or 'atic') set back with small windows at irregular intervals. These apartments today house a permanent exhibition of Gaudí memorabilia. Whereas most of the apartments are used as Caixa Catalunya offices (the bank owns the building), a lucky few still call La Pedrera home. One apartment is open and staged to give viewers a sense of such accommodations. The building is itself a museum, and features a collection of modern art paintings and renaissance drawings, while also hosting rotating exhibitions, lectures and film events. The building is part of the UNESCO World Heritage Site "Works of Antoni Gaudí", established in 1984.