The full name of this temple is quite a mouthful - The Basílica I Temple Expiatori de la Sagrada Família. This temple is the largest unfinished Catholic church in the world and is located in Spain's most popular tourist city, Barcelona, in Catalonia. The church was designed by Catalan architect Antoni Gaudi, who lived from 1852 to 1926. He never saw his piece of art finished.
Gaudi's work is a UNESCO World Heritage Site, and back in November 2010, it was consecrated by Pope Benedict XVI as a minor basilica, making it almost as important as a cathedral. Unfortunately, the minor basilica couldn't be made a cathedral, since it is not the seat of a bishop. Construction started in 1882, and funding relied solely on private donations, which is one of the reasons why construction was never completed.