The Cathedral of Saint Peter in Trier is the oldest cathedral in Germany. The edifice is notable for its extremely long life span under multiple different eras each contributing some elements to its design, including the center of the main chapel being made of Roman brick laid under the direction of Saint Helen, resulting in a cathedral added onto gradually rather than rebuilt in different eras. Its dimensions, 112.5 by 41 m, make it the largest church structure in Trier. In 1986 it was listed as part of the Roman Monuments, Cathedral of St. Peter and Church of Our Lady in Trier UNESCO World Heritage Site.
The structure is raised upon the foundations of Roman buildings of Augusta Treverorum. Following the conversion of the Emperor Constantine the Bishop Maximin of Trier (329-346) coordinated the construction of the grandest ensemble of ecclesiastical structures in the West outside Rome: on a groundplan four times the area of the present cathedral no less than four basilicas, a baptistery and outbuildings were constructed; the four piers of the crossing formed the nucleus of the present structure.
The fourth-century structure was left in ruins by the Franks and rebuilt. Normans destroyed the structure again in 882. Under Archbishop Egbert (d. 993) it was restored once more.
The West front in five symmetrical sections remains typical of Romanesque architecture under the Salian emperors. The West end choir, with its apsidal semi-cylinder expressed on the exterior façade, was completed in 1196. The interior is of three Romanesque naves with Gothic vaulting, and a Baroque chapel for the relic of the Seamless robe of Jesus, recovered from the interior of the high altar in 1512, complete the interior.
The skull of St. Helena, the mother of Emperor Constantine, is displayed in the cathedral.
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.