Pope Leo XIV has celebrated the Sagrada Familia Basilica as a masterpiece of “stones, colors and light.” He marked the centenary of the death of its architect, Antoni Gaudí, with a Mass. Leo called Gaudí’s unfinished temple, one of the world’s most visited monuments, a “sign of unity and harmony for all of Spain.” The service Wednesday was the highlight of Leo’s weeklong visit to Spain. It was the first visit by a pope in 15 years to the once-staunchly Catholic European country that, like many others, has experienced secularizing trends. The trip, though, has shown the country still has plenty of faithful Catholics who have turned out in droves to welcome the American pope.