Basilica of the National Shrine- Washington, DC

At 129,910 square feet, the Basilica of the National Shrine of the Immaculate Conception is the largest Christian Church in the United States. Built largely between 1924 and 1959, with a break during World War II, the Byzatine/Romanesque Revival shrine consists of 81 chapels, a Crypt Church and the Great Upper Church. 

Built in the style of medieval churches, the structure is supported by masonry walls, arches and columns rather than structural steel. The interior is adorned with magnificent murals and breathtaking tile mosaics, rivaling even the finest cathedrals in Europe.