A UNESCO World Heritage site and Antoni Gaudi’s magnum opus, is undoubtedly the most iconic structure in Barcelona (and the most popular, with nearly 3 million visitors per year). Construction has been ongoing for more than 135 years, and the surreal structure, with its rainbow-hued stained glass windows, is slated for completion in 2026. Even in its unfinished state, it remains an absolute must-see for every visitor to the Catalan capital. Antoni Gaudi is buried in the crypt of this Church. Some of these images were also capture in the historical museum in the basement which documents all aspect of the church.