Right next to the south station in Mainz (where the InterCityExpress trains go through without stopping) there is an archaeological excavation site called Theatrum Mogontiacensium. With the help of numerous volunteers, including local school children and also some of the Americans who used to live in the area, archaeologists have gradually uncovered the remains of a huge Roman theater that once had room for ten thousand spectators, which is roughly eleven times as many as can now be seated in the large hall of the State Theater in Mainz.
The wood-and-metal construction is meant to show the shape of the theater, and where the first six rows of seats used to be. Originally, there were many more rows of seats, going upwards and back from these. Archeologists have determined that in Roman times the cavea, or seating section, had a diameter of about 116 meters, making it the largest Roman stage theater north of the Alps, even larger than the ones in Arausio (Orange) and Arelate (Arles) in southern France.
The stage in Roman times was where the station and tracks are located now.
Ever since 1884, when this railway line was built, it has been known that the ancient Romans had something at this site. But exactly what it was, and how big, has only gradually become evident, especially during the years of systematic excavation since the beginning of the 21st century.
Mogontiacum was the Roman name for what is now Mainz and vicinity, and it was important to them particularly as a strategic location because of the confluence of the Main and Rhine Rivers.
In the 11th century, an historian named Gozwin wrote: “Hoc etiam astruunt adhuc superstites theatri ruinae, quod Romano more ad ludos circenses et theatrica spectacula constructum est”. Any questions?
The excavation site begins right next to the platform of track 4, with only a wire fence separating the platform from the site.
The site isn’t exactly open to the public, but that’s no problem since you can see into it through the fence from all sides. And they do give guided tours sometimes.
This railroad station, which for over a century was called Mainz Süd (meaning Mainz South) has now been re-named Mainz Römisches Theater (Mainz Roman Theater).
My photos in this post are from 2004. I revised the text in 2020.