Around 2,000,000 people annually visit Spanish architect Antoni Gaudi’s unfinished gesamkunstwerk, La Sagrada Familia–a massive church in Barcelona, which was begun in 1883. Since many of Gaudi’s plans for the structure were destroyed during the Spanish Civil War, teams of architects have been continually tinkering with the elusive structure since his death in 1926. Because Gaudi seemingly didn’t use regular or repeating forms–relying instead on color, light and organic sculptural motifs–architects working on the completion of La Sagrada Familia have faced a host of daunting design problems. In the 1980s New Zealand architect Mark Burry began using computer-aided design to piece together the missing parts–but traditional architectural software doesn’t translate Gaudi’s off-beat forms, so Burry applied aeronautical design software to the problem. Though slated for completion by 2007, the building is still very much under construction–the completion date having been pushed back yet again. As the structure is dedicated to the holy family, Gaudi would often joke, “The patron of this project is not in a hurry.” Gaudi: Unseen offers a behind-the-scenes look at this hundred-year-long architectural drama.