The Basilica of the Immaculate Conception is a prominent Roman Catholic church located in Washington, D.C. It is the largest Catholic church in the United States and serves as a national shrine. The basilica is dedicated to the Immaculate Conception, a doctrine that teaches that the Virgin Mary was conceived without original sin. Construction of the basilica began in 1920 and was completed in 2017, featuring stunning architecture that combines Romanesque and Byzantine styles. The interior is adorned with beautiful mosaics, chapels, and artwork, making it a significant site for both worship and tourism.