In 1883, Antoni Gaudí, the great Catalan architect, began working on his magnum opus, the Sagrada Família, the church that has become one of the most popular tourist attractions in Barcelona. Before his death in 1925, Gaudí managed to complete the crypt, apse and part of the Nativity facade. Work on the basilica slowed during the 1930s and 40s, especially during the Spanish Civil War, but picked up again in the 1950s. A series of architects carried on Gaudí's work, completing new towers and facades. In 2000, the central nave vaulting was completed, and, since then, modern technology has put architects on track to complete the church decades ahead of schedule. The new target date is 2026 -- the centenary of Gaudí's death. Thanks to a computer-generated video released by the Sagrada Familia Foundation, you can see what the basilica, almost 150 years in the making, will look like when it's all done. You can also take a virtual tour of the interior of the UNESCO landmark here.