Pope Leo XIV will bless the giant new tower of the famed Sagrada Familia Basilica in Barcelona on Wednesday and celebrate mass inside what is now the world's tallest church. The church is a still-unfinished modernist masterpiece by architect Antoni Gaudi that was visited by nearly five million people last year. The pope's visit during a week-long trip to Spain coincides with the 100th anniversary of Gaudi's death on June 10, 1926.