An 800 BC Ethiopian wall could have carried sixteen storeys, models show

The reconstruction of Grat Be’al Gibri shows eight storeys, and sixteen is what its walls could theoretically have borne under worst-case assumptions about the building materials. The gap between the two figures, drawn from a finite element model of a palace in Yeha, northern Ethiopia, is the central result of a 2026 structural study by Martin Drieschner and Mike Schnelle.

The palace dates to about 800 BC, roughly 2,800 years ago, and covered some 60 by 60 metres. Its ground-floor walls were 1.9 metres thick, set on a foundation podium with walls 2.2 metres thick and standing about six metres high. The question the two authors put to the ruins was an engineer’s rather than an archaeologist’s: with walls built of rubble, clay and timber, how much load could the surviving system take before it failed?

Rubble, clay mortar and horizontal timber

The walls were built from locally quarried phonolite rubble set in clay mortar and bonded with horizontal wooden beams laid through the masonry. According to HeritageDaily’s summary of the paper, the timber was African olive and Cordia africana, species chosen for pest resistance, and the beams run in a purely horizontal arrangement, which sets the building apart from comparable South Arabian structures.

Yeha is home to what Wikipedia’s entry on the site calls the oldest standing structure in Ethiopia, the Great Temple, and the palace is its largest known building. The German Archaeological Institute’s research blog calls the palace “the largest stone-and-timber building in East Africa and South Arabia.” The neighbouring Great Temple, built in the seventh century BC in a South Arabian tradition and later consecrated as a church, still stands 14 metres high, and a catastrophic fire destroyed the monumental buildings around the middle of the first millennium BC. A joint Ethiopian-German project with the University of Jena, funded by the German Research Foundation since 2016, has been working at the site, and Yeha’s longer record of exploration reaches back to Theodore Bent’s visit in 1893 and systematic excavations from 1952.

Finite element models of two wall sections

Drieschner leads a structural dynamics group at the Brandenburg University of Technology Cottbus-Senftenberg and specialises in modelling uncertain material properties. He worked with Schnelle of the German Archaeological Institute on a three-dimensional virtual reconstruction of the palace, and the two analysed a pair of representative sections: an external wall corner and an internal wall containing a doorway.

Nobody can load-test 2,800-year-old clay mortar, so the models treated material strength as a range of plausible values, not one number. The paper, titled “Numerical Investigations of Timber-Reinforced Wall Constructions with Uncertain Material Parameters” and published in the journal Heritage in 2026, found that variation in the wood properties had very little influence on the outcome. The properties of the clay-mortared rubble masonry mattered far more, which is why the 16-storey figure is tied to the worst-case masonry assumption and not to the timber.

Sixteen storeys as capacity, eight as reconstruction

The authors conclude that “a multi-story building was feasible with the present wall constructions.” Under the worst-case masonry, the walls could theoretically have risen to as many as 16 storeys while remaining structurally stable, while the eight-storey reconstruction sat “comfortably within the walls’ theoretical load-bearing capacity,” in the paper’s phrasing as reported by HeritageDaily.

The model measures capacity and nothing more, and the study draws that line itself: the result “does not mean that Grat Be’al Gibri actually had 16 floors.” What it shows is that the surviving wall system could carry substantially more weight than the reconstructed building would have imposed. Structural analysis alone cannot fix how many floors were really built, because the building’s original upper floors are not preserved to be counted.

The fire evidence fits the engineering result. If ordinary loading could not have brought the walls down, then, as the authors put it, “an exceptional load must have caused the system failure,” and the archaeological record points to a blaze in antiquity. The builders at Yeha, in the authors’ reading, had arrived at highly efficient structures through experience and the passing-on of knowledge, long before anyone could calculate a safety factor.

Worst-case modelling is a conservative way to ask the question. Engineers assign the weakest values that the evidence allows to every uncertain material, run the simulation, and see whether the structure still stands. If it does, anything stronger in reality only adds margin. That logic is what gives the sixteen-storey figure its meaning as a ceiling on what the walls could take, and it is also why the figure cannot be read as a count of floors that anyone built or used.

What the palace’s real height was remains unresolved, and a model cannot settle it.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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