The shrine is the largest Catholic church in the United States and North America, one of the ten largest churches in the world, and the tallest habitable building in Washington, D.C. Construction of this church, notable for its Neo-Byzantine architecture, began in 1920 under Philadelphia contractor John McShain. It opened unfinished in 1959. Completion of the Trinity Dome -- dedicated on December 8, 2017 -- marked the completion of the building. The Shrine hosts an estimated one million pilgrims each year.
The basilica is designated both as the national and patronal Catholic Church of the United States, honoring the Virgin Mary, under the title Immaculate Conception, by which Pope Pius XI donated a mosaic of the same image in 1923. The basilica is not the cathedralchurch of the Archdiocese of Washington as the Cathedral of St. Matthew the Apostle has served in this capacity since the creation of the archdiocese in 1939.
The shrine hosted Popes John Paul II, who designated the National Shrine as a Minor Basilica on October 12, 1990; Benedict XVI, who bestowed the honor of a Golden Rose on the basilica on April 16, 2008; and Francis, when he celebrated Mass on the east steps for the canonization of Junípero Serra, O.F.M. on September 23, 2015.
The basilica does not have its own parish community, but serves the adjacent Catholic University of America which donated the land for its construction, the United States Conference of Catholic Bishops, and hosts numerous Masses for various organizations of the Church from across the United States.
The rector of the shrine is the Monsignor Walter R. Rossi, who holds a Licentiate of Canon Law.
The basilica is on Michigan Avenue in the northeast quadrant of Washington. It is served by Brookland-CUA Metro Station on the Red Line, roughly 0.3 miles (0.5 km) away.