During my visit to the Roman city of Trier, I visited the Porta Nigra, the colossal Roman city gate. It is not only the symbol of Trier, but also the best-preserved Roman city gate north of the Alps. The city of Trier was founded as Augusta Treverorum in 17 BC and is the oldest city in Germany. When I saw the imposing city gate, I was immediately fascinated. It was not only gigantic, but also black. The white sandstone changed color over the course of more than a thousand years. I was impressed by this monumental structure, which was built around 170 AD from approximately 7,200 stone blocks. Thanks to its solid construction from sandstone blocks weighing up to six tons, it has been preserved to this day. The sandstone blocks were cut to size using mill-driven bronze saws and stacked on top of each other without mortar. However, two stones were joined horizontally by iron clamps cast in lead. I could see these clamps inside the gate near the eastern spiral staircase. Traces of rust from former clamps can still be seen on the outside, as deep holes were chiseled in the Middle Ages to steal the metal and melt it down. After 1028, the Greek monk Simeon had himself walled into the east tower of the Porta Nigra as a hermit. When he died in 1035, he was buried on the ground floor and canonized. Archbishop Poppo of Babenberg had two churches built one above the other in the Roman gate in his honor. These were demolished under Napoleon’s rule between 1804 and 1809, and a reconstruction of the ancient building was ordered. Traces of the double church and Roman stonemason’s marks can be found inside the city gate. I was able to access all the information about the Roman city gate free of charge via a multimedia app. I was thrilled by this new generation of digital guided tours and explored Trier’s absolute visitor magnet, which has been included in the UNESCO World Heritage List, in this way. Trier has a total of nine UNESCO World Heritage Sites.
