The basilica is[3] dedicated to the Blessed Virgin Mary as the Immaculate Conception, designated as the principal Patroness accorded by Pope Pius IX on February 7, 1847.

Pope John Paul II raised the National Shrine to the status of Minor Basilica via his Pontifical decree Clarum Constat Templum on October 12, 1990.

Artist Jan Henryk De Rosen, who presided over the shrine's iconography committee was also responsible for much of its decor, including composing the large mosaic over the northern apse.

[7] The shrine was built in the style of medieval churches, relying on thick masonry walls and columns in place of structural steel and reinforced concrete.

It was designed to hold 10,000 worshipers and includes modern amenities such as a basement cafeteria, hidden public address speakers to carry speech at the altar to the rear of the building, air conditioning and what was the largest radiant heating slab in the world (in 1959).

[8] There are arches outlined with iridescent Pewabic Pottery tile, large ceramic medallions set in the ceiling, and fourteen Stations of the Cross in the Crypt Church.

Bishop Thomas Joseph Shahan, the fourth rector of the Catholic University of America in Washington, D.C., proposed the construction of a national shrine to commemorate the Immaculate Conception in the country's capital.

Shahan returned to the United States and persuaded the board of trustees of The Catholic University of America to donate land at the southwest corner of the campus for his shrine.

He wrote that the shrine would be a "monument of love and gratitude, a great hymn in stone as perfect as the art of man can make it and as holy as the intentions of its builders could wish it to be."

[11] On May 16, 1920, Archbishop Giovanni Bonzano, Apostolic Nuncio to the United States of America, celebrated Mass and blessed the site of the future National Shrine.

[14] In 2008, during his trip to the United States, Pope Benedict XVI bestowed the Golden Rose upon the Basilica of the National Shrine of the Immaculate Conception.

[16] On January 26, 2013, the basilica held a televised thanksgiving Mass and enshrined two first class relics of Americans Kateri Tekakwitha and Marianne Cope, who were both canonized October 20, 2012.

[17] Pope Francis visited the shrine on September 23, 2015, and celebrated a Mass for the canonization of Saint Junípero Serra, O.F.M., on the mall of the Catholic University of America.

[19] The final architectural element was completed with the installation of the 24 tons of Venetian glass in the central Trinity Dome, one of the largest mosaics of its kind in the world.