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Constantine’s twin basilica at Trier Rowe, Ria Theresia


Founded during the reign of Augustus, most probably during the Emperor's presence in Gaul in 16-13 B.C., Trier became a colonia during the reign of Claudius around 50 A.D. The Colonia Augusta Trevexorum became the seat of the Roman administration in the first century A.D. and prosperity and wealth made her one of the most important cities in the northern Roman Empire, and one of the capitals of the western Empire in the late third century. Constantius Chlorus became Caesar of the northern Empire in 293 and with him began a close relationship between the House of Constantine and the City of Trier, which was to last well over fifty years. Constantine the Great lived here for ten years until 315 and his sons resided in the city after him until 348. An immense building program marked the late great flowering of the Roman city, and in 326 A.D. the huge twin basilica was built on the ruins of an imperial palace. Legend has linked Helena, mother of Constantine the Great, with the foundation of Trier's cathedral and also with the translation of the Holy Robe from Jerusalem to the cathedral at Trier. Excavations in the area of Trier's cathedral, undertaken by Dr. Th. K. Kempf since 1943 have revealed remains of a twin basilica built on the site of a Constantinian palace between 326 and 348. It was also established that the square sanctuary of the North. Basilica was expanded and rebuilt by Gratian in 370-380 A.D. on foundations of a Constantinian square sanctuary. In the past archaeologists had assumed that this part, dating from the reign of Gratian was a single unit and only more recently did scholars speculate that this square structure was possibly a part of a larger basilica. However, it was not until the year 1943 that the foundations of a basilical hall were discovered below the cathedral square, confirming the assumptions made by archaeologists in the 1920's. With the extensive destruction suffered by the Dom and Liebfrauen church (cathedral and Church of Our Lady) during the last year of World War II further opportunity was given to the archaeologists to excavate. In 1948 and subsequent years Roman foundations of Constantinian age were discovered also below the neighbouring Liebfrauen church, which confirmed the presence of a twin basilica, a fact which had been assumed since 1943. Trier's twin basilica was large; each church holding about 6000 people. The whole complex covered an area of a double insula in the street system along the north-eastern part of the Roman city within a huge palace district. The twin basilica comprised two longitudinal halls of equal length and almost equal width; each had an atrium and a transept-type narthex to the west and a rectilinear termination to the east. The two basilicas were joined by a three-aisled hall in the east and a square baptistery in the west. The north basilica was slightly larger and had a monumental, triumphal arch-type entrance toward the street. Bases of an altar were discovered in the south basilica but not in the north. A polygonal structure within the square sanctuary was added to the north basilica soon after the basilica was built which has been interpreted as a memoria. The complex was built between 326 and 348 and the south basilica was finished first. Whereas the basilical halls remained almost unaltered throughout the Constantinian era, the sanctuaries in both churches underwent three, even four building phases. Germanic invasions left their mark on the City of Trier and also the twin basilical complex, and under the late great flowering during the reign of Valentinian and Gratian the square sanctuary of the north basilica was expanded and rebuilt. The rising walls of this building are still visible, in parts up to about 100 feet high, and are the oldest part of the present Dom. The Twin Basilica at Trier is unique among Constantinian church foundations both in dimension and importance. Each single basilica of the complex can be likened to St. John Lateran in Rome in their first building phases and accommodating only slightly less people than the Lateran church. With the erection of the Polygon in the north basilica comparisons can be made between it and the martyrium-basilicas in Jerusalem and Bethlehem. A convincing argument concerning a christological relic at Trier put forward by Dr. Th. K. Kempf in his article on The Robe at Trier's Cathedral, describes the north basilica as such a martyrium-basilica, the south basilica retaining its form and function as before. It has now been firmly established that both basilicas were restored during the Merovingian and Carolingian epochs and existed as a complex until the Norman invasions and the sacking of the city in 882 A.D. Thus the author of the Vita S. Helenae, Almann von Hautvillers, actually saw the Constantinian twin basilica, a fact which makes the legend of the donation by Helena of her palace to the city of Trier more credible. The discovery of the ceiling frescoes from a palace below the Constantinian north basilica and dating from before 326 A.D. gives further credence to the Helena tradition. The frescoes were discovered in an excellent state of preservation and three of the panels were interpreted as being portraits of members of Constantineis immediate family. Comparisons have been made with the donor mosaics in the south hall of the twin complex at Aquileia which are most probably contemporary with the Trier frescoes. Other twin basilicas of the fourth century, as catalogued in the Appendix, appear to have been confined- to the Adriatic and northern Italy with one in North Africa and possibly two in the Holy Land. But it is evident that the Twin Basilica at Trier stands out as a unique monument among Constantinian church foundations presenting a different dimension.

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