Basilica of the National Shrine of the Immaculate Conception (largest Catholic church in the U.S.)

The Basilica of the National Shrine of the Immaculate Conception in Washington, D.C., is commonly described as the largest Catholic church in the United States and one of the largest Catholic churches in the world by interior area and seating capacity. Construction began in 1920 and the complex contains extensive mosaics, chapels, and a large domed nave used for national liturgies and pilgrimages. Rankings of 'largest' churches can vary by measurement criteria, so comparisons are sometimes debated.