Gaudí created many extraordinary buildings in Barcelona in the early 20th century. His Art Nouveau-inspired works include the Casa Mila and Casa Batllo apartments, known from their undulating façades, and several works for patron Eusebi Guell, including the Parc Guell, a park in Barcelona. He spent 40 years working on the Expiatory Church of the Holy Family (also known as La Sagrada Familia), which will be finished in 2026. He was also fond of using hyperbolic paraboloids in his work.