3. Gaudi’s Sagrada Familia

Perhaps the longest running architectural project in recent memory, the Sagrada Familia is a massive and uniquely designed Roman Catholic cathedral in Barcelona that has been under construction since 1882. The building was designed by famed architect Antoni Gaudi, and was considered to be his crowning achievement. Gaudi worked on the church for forty years, and even devoted his last fifteen years exclusively to it, but he died in 1926 before it was completed. The project was then taken over by Gaudi’s assistants, who continued work on it even after it was badly damaged by anarchists during the Spanish Civil War. Since then, the project has been in a constant state of flux, with a number of different architects and builders coming on to it, but it has yet to be opened or actively used as a church. Even in its unfinished state, the Sagrada Familia is Barcelona’s most famous tourist attraction, and authorities have claimed that the building may finally be open to the public by 2010.