At Hadrian's Villa a slab marks the spot struck by a night lightning bolt

The morning had declared the Culture section’s discovery. The find is an archaeological discovery with four origins that converge: a marble slab of about 40 by 35 centimeters, with two words carved on it, found where it had been placed.

The inscription reads FVLGVR SVBMANIVM. The reference is to Summanus, the Roman deity of nocturnal lightning: the formula indicated that a bolt attributed to the god had struck that point and that the place had been treated accordingly. The find was identified in the area of Hadrian’s Villa, in Tivoli, known as the Amphitheater, during excavations by the University of Urbino Carlo Bo carried out under concession from the Ministry of Culture together with the Institute of Hadrian’s Villa and Villa d’Este. The news is reported by Archaeology News Online Magazine, Discover Magazine, La Brújula Verde and The History Blog.

Why the position matters, not the object

Inscriptions with this formula are known to scholars. What makes the Tivoli find different is that the slab was not found reused in a wall, nor in a storeroom, nor in a fill layer: it was still in its original placement, set into a small quadrangular structure built with tuff blocks.

This means the context is legible. An inscription out of place documents a practice; an inscription in its place also documents the how: the structure that contained it, its relationship with what surrounds it, the level at which it is found relative to earlier and later strata.

The rite of the fulgur conditum

The practice to which the inscription refers is that of the fulgur conditum, the “buried” lightning bolt. The struck point was delimited and treated as sacred, and an inscription recorded its nature. It is a part of Roman religiosity that leaves few material traces, because it consists of a gesture performed only once at a precise point.

Alberto Samonà, director of the Institute of Hadrian’s Villa and Villa d’Este, has observed that the discovery shifts the focus of attention from grand architecture toward a more intimate dimension of Roman religiosity. Fabio Giorgio Cavallero, director of the excavation for the University of Urbino Carlo Bo, indicates that the find opens new perspectives on the history of this sector of the villa and on the role that the rite played in the reorganization of the spaces. Both assessments come from the official excavation communication, and we report them as such.

The stratigraphic question

There is an open question that archaeologists have already raised. In the same area, in 2024, a palace subsequently demolished and buried had been identified. Research will now have to establish the sequence between the two events: does the lightning rite precede the demolition, follow it, or is it linked to the reorganization of the area? The answer does not lie in a reading of the inscription but in the reading of the strata, and it is work that requires time.

After the announcement, the Minister of Culture Alessandro Giuli went to Hadrian’s Villa.

What we do not know

The available sources do not provide a dating for the slab nor for the event it records. They do not indicate whether the surrounding area has yielded other elements connectable to the rite, nor what relationship the tuff structure bears to the layout of the Amphitheater. Finally, they do not contain a date for the scientific publication of the results: so far there is the excavation announcement, not the study.

The object, in any case, is now a fixed point on the plan of Hadrian’s Villa: two words on a marble slab of about 40 by 35 centimeters, left in the tuff structure in which it was placed.