The Basilica of the National Shrine of the Immaculate Conception 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. An estimated one million pilgrims visit the basilica 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 houses 70 chapels honoring Mary and reflecting the origins of the Catholic immigrants and religious orders whose generosity erected them. Its Greek-styled interior is crowned with numerous domes 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 152m long, 73m wide, and 72 m tall to the top of the cross on the dome. The shrine was built in the style of medieval churches, relying on masonry walls and columns in place of structural steel and reinforced concrete. It was designed to hold 10,000 worshipers.
In all, 70 chapels and sacred images flank the sides of the upper church and crypt. It contains many works of art. There are arches outlined with iridescent Pewabic Pottery tile, large ceramic medallions set in the ceiling, and fourteen Stations of the Cross for the crypt.
References:The Clementinum is a historic complex of buildings in Prague. Until recently the complex hosted the National, University and Technical libraries, the City Library also being located nearby on Mariánské Náměstí. The Technical library and the Municipal library have moved to the Prague National Technical Library at Technická 6 since 2009. It is currently in use as the National Library of the Czech Republic.
Its history dates from the existence of a chapel dedicated to Saint Clement in the 11th century. A Dominican monastery was founded in the medieval period, which was transformed in 1556 to a Jesuit college. In 1622 the Jesuits transferred the library of Charles University to the Klementinum, and the college was merged with the University in 1654. The Jesuits remained until 1773, when the Klementinum was established as an observatory, library, and university by the Empress Maria Theresa of Austria.