Comments about the building and its ancient, medieval and early modern history and use have been made over centuries. There is also a considerable number of historical documents that allow various hypotheses about the building or construction. It was an ancient city gate, which was extended in the Middle Ages by the construction of a collegiate church. However, on the other hand, these statements were so generalizing or general, not to say topical, that the research did not really progress. Always only preliminary results were published. Thus one asked oneself for the antique building phase when the Porta Nigra was actually built and whether it was completed at all. Some features had long been interpreted as unfinished but this was hypothetical. For them, there were different reasons: one had not finished or vandals had threatened Trier and interrupted the progress of construction, and so on. It was also not quite clear when the construction of the church took place, which Caspar Merian handed down in an engraving dated 1670. Such building masses had to leave traces in the building, in the documents and sources as well as in the material stores, which in Trier consisted primarily of other antique buildings. The research results published up to the second half of the 20th century, therefore, had to leave gaps to a greater extent than they would have given a complete picture of the history of the building.
Since the Porta Nigra has never been spared:
- Already in the Middle Ages, the iron clamps were stolen, which held the stone blocks together.
- The collegiate church of St. Simeon was built at the top.
- In the 18th century, rococo ornaments and other reliefs were worked into and out of the surfaces of the ancient stones.
- Finally, it was partially restored to its ancient origins and was to serve as a museum.
- In the 20th century, tanks were clattering through the gates.
- And even today buses run at intervals of a few meters, which is actually a scandal.
- The reconstruction of the tourist development in the 20th century also did not bring any stabilisation.
At the beginning of this century, it was decided to restore Porta Nigra. However, it was not a question of removing the dark patina. This is due to a chemical change in the stone. On the other hand, it was planned to preserve and strengthen the building as a whole.
This project was funded by the State of Rhineland-Palatinate and the German Research Foundation. The two projects, scientific research, and definition of the construction, conversion and use phases, which serve as the basis for the planned refurbishment, ran parallel for a while. The research project “Porta Nigra” is finished in its duration (funding). Unfortunately, not all the results are available in the form one would have wished. But at least: The Building Research Institute (DAI) compiles the results in a book to be published in the next few years (Birte Geißler); there is a room book of more than a thousand pages and a large number of photographs of the elements of the building, be it 3D scans or hand-made drawings/photographs/plans, etc. (especially Birte Geißler), be it the results of the examination of the plasters, dating of the woods found in the building or also outside, etc. All these results of the preliminary investigation are now in the hands of LBB. Also in print is a work on the transformations and concepts of the 18th century (Martina Kancirova, to be published in 2020). It shows to what extent the humanistic concept of “Renovatio” found its form in the new furnishings of the late Baroque / Rococo period. Unfortunately, the research on the medieval Porta Nigra / Simeon Monastery, whose complexity was underestimated, has not been completed and is still a desideratum of research – among other things because a large part of the findings has been lost due to the centuries-long transformation of the buildings. In addition, there have been radical changes in the assessment of the building substance since the DAI’s renewed research into the building.
However, the results, albeit partly provisional, are no less sensational. In the past – until the publications of Gose and other archaeologists or the research of Heyen, yes until the beginning of the campaign in the second decade of the 21st century – the Porta Nigra was dated with different reasons into the 2nd and 3rd centuries, even into the beginning migration period. Moreover, one was not quite sure whether the building was completed at this time at all. It was repeatedly described as “unfinished”.
Building research/archaeology now has clear evidence for both archaeological questions, while those of art history still awaits further research:
– Dating and condition of the building:
The dendrochronological analysis of the discovery of a piece of wood in the immediate vicinity of the Porta Nigra revealed a date from around 170 AD. The origin of this best-preserved town gate north of the Alps can now be precisely limited to the last quarter of the 2nd century.
Moreover, the findings of building research have shown that many external surfaces of the Porta Nigra, in particular, the capitals, are located in the Bosse. This means that they were moved during construction without having been completed before or after. In other words, the ancient Porta Nigra was never completed and can certainly be dated back to the second century AD.
– Post-antique building phases:
The medieval and the early modern collegiate church of St. Simeon was initially NOT built in the 11th century. It consisted of the liturgical use of the Porta Nigra first as a seat (“dwelling”), then as the tomb of Saint Simeon. Until 2015 (!) it was assumed that the engraving made by Merian in 1670 already represented the situation in the 11th century. One suspected that due to the medieval forms (capitals, friezes, windows, and other building forms) several construction phases were to be assumed (Irsch). But one did not want to give up the sensation of such building volumes and usage strategies, i.e. a monastery and a collegiate church, which almost outshone the Trier Cathedral, for the 11th century. Because these building forms – a building with a dwarf gallery, possibly ribbed vaults and an open staircase that could only have been described as sensational in Rome – would have catapulted Trier to the beginning of high medieval architecture. It would also have posed questions to art history that it would hardly have been able to answer.
The investigations of building research and art history, however, came to a different conclusion. When the Porta Nigra was “put into operation” as a collegiate church, i.e. in the 11th century, the year of the canonization and burial of St. Simeon, there were no structural changes in the Porta Nigra, apart from a vault and a wall in a room on the ground floor of the east tower. All historical reports and sources only allow the conclusion that the Porta Nigra (!) served as the burial place of the saint and was liturgically “converted” by installing altars and making the graves of the saint and his mediator, the archbishop of Trier, Poppo von Babenberg, accessible. This created a liturgical place, but not a high medieval church! This means that the Simeons monastery next to Porta Nigra, which was built in the 11th century on the basis of a dendrochronological dating, may also date back to the 12th century and later, as can be seen from the building forms, some of which are still original today (here too there were many transformations). It can hardly be assumed that these building forms typical for the high Middle Ages – which would also have been a sensation and difficult to explain – can be attributed to the early Middle Ages, i.e. the 11th century. A swallow doesn’t make a summer yet!
Finally, the over formations of the early modern period in the 18th century have been investigated. Here a comprehensible and little surprising, but in the execution singular result has turned out: the generally conservative attitude of the middle and the late 18th century, also known as “Renovatio” and often communicated by the canons, was not only intellectually but also formally adopted. It led to the triumph of the actually obsolete use of the rocaille and thus to a connection, but also to compete with other buildings in this formal design (e.g. St. Paulin).