Let this be a warning to you if you’re considering installing underfloor heating.

St Johannis is the 2nd oldest cathedral in Germany, having been consecrated in 910, but likely having been built at the end of the 8th century.

Much architectural fiddling about (12C: bowl the transept, 1685, raise the floor by 2 meters, 1737, bowl the east apse and on and on. As one does) occurred between then and 1792 when the French occupying force closed it down, using it as a warehouse and resuling in the coup de grace via a Reich Deputation Main Resolution which basically said “Well, you’re not a church any more”

To which in 1828 (took them a while to catch on…), the Protestant community said “Well, we’ll have it, then”, rolled up their sleeves and fiddled architecturally until it was re-consecrated (but without the incense etc) in 1830.

Waste of time and money.

Along comes the RAF in August 1942 and bowls St Johannis (along with big chunks of the city).

Rebuild, reconsecrate (1956) and carry on restoring.

2013 is where it gets interesting.

Underfloor heating planned, so up comes the existing floor and – oops, what do we have here?

The old floor. Let’s dig a bit deeper.

Oh, something Roman from 1C.

And what’s this?

Bloody hell, it’s a sarcophagus with the remains of Erkenbald, Archbishop of Mainz from 1010-1021.

And they’re still digging….

27 Oct This entry was published on 27 October, 2025 at 09:00. It’s filed under Altstadt, Architecture, Cool stuff, History, Mainz and tagged Mainz, St Johannis. Bookmark the permalink. Follow any comments here with the RSS feed for this post.