Gaudí's 1912 undulating Passeig de Gràcia apartment block — Wave-like stone facade. UNESCO 1984.
From Wikipedia
Casa Milà, popularly known as La Pedrera in reference to its unconventional rough-hewn appearance, is a Modernista building in Barcelona, Catalonia, Spain. It was the last private residence designed by architect Antoni Gaudí and was built between 1906 and 1912.