An important moment for the realisation of the origins of the arch occurred at the beginning of the twentieth century, when the young German archaeologist Fritz Töbelmann, who had been studying it for five years, came to the conclusion that the arch was built before the end of the fourth century. Töbelmann came to this position thanks to a detailed inspection of the construction, in the course of which he discovered a brick stamp from the era of Diocletian (r.284-305) under the plaster on one of the bricks of the arch's central vault. This allowed him to demonstrate that the date of the monument's construction could not be earlier than this period.
