#1. Sagrada FamíliaWhat Frank Gehry and Frank Lloyd Wright are to the US, Antoni Gaudí (1852–1926) is to Barcelona, Spain. Sagrada Familia is one of the masterpieces designed by the all-time great architecture Antoni Gaudí. The architecture is part of the UNESCO World Heritage Site. You would be surprised to know that this is still an unfinished Roman Catholic Church. Its construction started in 1882. However, only 70 percent progress has been made. Visitor entrance fees of 15–20 euros (17.17 USD to 22.89 USD) finance the annual construction budget of 25 million euros.