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 Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.