decorated in mosaics, similar to the Basilica of St. Mark in Venice, Italy, but much larger. The mosaics feature American renditions of traditional Catholic images. 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. The exterior of the basilica is long, wide, and tall to the top of the cross on the dome. The exterior area of the basilica is . The diameter of the main dome (the Trinity Dome) of the basilica is only smaller than that of the dome of the U.S. Capitol. The interior area of the basilica is for the Upper Level and Great Upper Church, and for the Lower Level and Crypt Church, for a grand total of . 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). 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. History Patronage of the Immaculate Conception In 1792 John Carroll, the bishop of Baltimore and the United States's first Catholic bishop, consecrated the newly created United States under the protection of the Blessed Virgin Mary under the title of the Immaculate Conception. In 1846, the 6th Provincial Councils of Baltimore reiterated this episcopal choice to name the title Virgin Mary, conceived without sin as the principal patroness of the land. Pope Pius IX formalized the decision on February 7, 1847, and it was published on July 2, 1847. Construction (20th Century) Bishop Thomas Joseph Shahan, the fourth rector of The Catholic University of America in Washington, proposed the construction of a national shrine to commemorate the Immaculate Conception in the country's capital. Bishop Shahan took his appeal to Pope Pius X on August 15, 1913. Shahan received the pope's enthusiastic support and personal contribution of US$400 (US$11,681 in 2022, adjusted for inflation). Shahan returned to the United States and persuaded the board of trustees of The Catholic University