An extraordinary discovery in the German city of Constance has revealed that the ceiling of a medieval cellar was constructed using the remains of an old ship.
Researchers believe much of the vessel’s hull may have survived, potentially offering rare new insights into medieval shipbuilding on Lake Constance.
The discovery was made during an architectural investigation of a property in Konradigasse, where specialists from the State Office for Monument Preservation discovered that timber covering more than 25 square metres of the cellar ceiling had once formed part of a medieval vessel.
The cellar itself dates to 1244, but the age of the ship has yet to be established. Samples of its timber are now undergoing dendrochronological analysis, which could reveal when the trees used to construct the vessel were felled.
What initially appeared to be a straightforward example of reused medieval timber quickly developed into a much more significant archaeological discovery.
“At first, all that was clear was that the planks had been reused. The fact that they were originally part of a ship was the complete surprise,” said Dr Aline Kottmann, a specialist in medieval archaeology at the State Office for Monument Preservation.
Almost an Entire Ship Hull May Have Been Reused
Recycling timber from vessels was not unknown during the Middle Ages. Ships that had reached the end of their working lives represented a valuable source of construction material at a time when large quantities of processed timber required considerable labour to produce.
What makes the Constance discovery particularly unusual is its scale.
Rather than a handful of isolated ship timbers being incorporated into the building, researchers believe an almost complete section of hull may have been reused.
The ceiling covers more than 25 square metres and contains at least 19 planks identified as ship components through distinctive features including wooden pegs, rows of fastening holes and characteristic plank shapes.
The discovery therefore provides evidence not only for medieval maritime technology, but also for the recycling and reuse of valuable raw materials in medieval construction.
Medieval Cargo Ship
Preliminary investigations suggest the timbers belonged to a flat-bottomed sailing cargo vessel.
The ship may have resembled other medieval vessels known from the Lake Constance region, including the 14th-century Kippenhorn wreck discovered near Immenstaad.
Researchers are particularly interested in determining whether portions of the vessel’s side planking have survived.
If confirmed, these sections could help archaeologists understand how medieval shipbuilders constructed the transition between the flat bottom of a vessel and its sides — an aspect of construction that can be difficult to study from the relatively small number of surviving medieval wrecks.
The unusual location of the timbers also makes them considerably more accessible than archaeological shipwrecks lying beneath Lake Constance.
Medieval Ship Repairs Still Visible
The surviving planks are revealing details about the vessel’s working life before it was dismantled.
Researchers have identified several areas where damaged timber was carefully removed and replaced with precisely shaped wooden inserts. At least four repairs have already been recognised.
One is particularly intriguing: a dovetail-shaped wooden insert for which researchers currently know of no direct parallel in medieval shipbuilding from Lake Constance.
Some of the planks also remain connected in much the same way as they would have been aboard the original vessel.
The boards were carefully shaped to fit together and were subsequently installed in the cellar ceiling while still joined.
Remarkably, traces of caulking — the sealing material placed between planks to prevent water entering the hull — have survived in some areas.
Researchers have taken samples of this material for analysis, potentially revealing more about the substances and techniques medieval shipwrights used to make their vessels watertight.
Ship Digitally Reconstructed
In mid-August 2026, specialists returned to the site to carry out detailed documentation of the discovery.
The ceiling was recorded using structure-from-motion photogrammetry, or SfM, a technique that creates detailed three-dimensional models from large numbers of overlapping photographs.
Hundreds of images were taken and are being digitally combined to produce a comprehensive 3D record of the surviving ship timbers.
Researchers also removed wood samples for dendrochronology. Analysis of the timbers could provide a much firmer date for the vessel and potentially establish whether the ship was already old when its planks were incorporated into the building.
Rare Window into Medieval Life on Lake Constance
The discovery comes as researchers are already investigating Lake Constance’s submerged archaeological heritage through the “Wrecks and Deep Sea” project, which is searching for surviving shipwrecks beneath the lake.
Medieval wrecks from the region are comparatively rare and, because surviving examples lie underwater, detailed archaeological investigation can be difficult.
The Konradigasse timbers offer a very different opportunity.
Preserved above water and incorporated into an accessible building, they could allow specialists to examine construction details that would otherwise be extremely challenging to document.
Researchers believe the find could ultimately provide important evidence about the vessels that once transported people and cargo around Lake Constance during the Middle Ages.
“The find goes far beyond a chance discovery,” Kottmann said, describing the timbers as valuable evidence of medieval shipbuilding technology and an important discovery for the maritime archaeology of the Lake Constance region.
For now, many questions remain unanswered — including precisely when the vessel was constructed, how long it sailed and when it was finally dismantled.
With dendrochronological and other analyses still under way, researchers emphasise that their conclusions remain preliminary. Further results are expected to reveal more about the remarkable medieval ship that, after its life on the water ended, found a second purpose hidden above a cellar in Constance.
Sources : Regierungspräsidium Stuttgart
