In the latest years, the “invisible town”, also called “Todi underground” unfolding under the surface area of Piazza del Popolo, the ancient Roman Forum, has been rediscovered and analysed in-depth, thanks to Todi Speleological Group’s skilful investigative work.
By using a model approach of “urban speleology” whereby underground exploration would interchange with archival research on historical and cartographic documents, a complex of more than thirty pre-Roman, Roman and Medieval cisterns was brought to light, together with five-hundred wells of different shapes and ages. They were running along more than five kilometres, making the subsoil of Todi a priceless heritage.
Thanks to the commitment of the Municipal Authorities in collaboration with Umbria Archaeological Authority, part of such monumental structures can be currently visited on the Western side of the square. Twelve rectangular rooms made of Roman concrete and covered by barrel vaults extend approximately eight metres in height, eight metres in width and thirty metres in length, with a capacity of approximately thirty-thousand cubic metres of water. The rooms communicate with one another through arched passageways and display one or more openings in the vaults, where water could be drawn from. Traces of the wooden formworks where the composite of stones and mortar was thrown are still visible on the walls.
The whole complex was rediscovered by chance on the occasion of the restoration works of the above Pazzaglia-Valentini tobacco shop. In terms of size, the structure occupies the initial stretch of via del Monte, and continues along via Valle Inferiore up to via Mazzini. In terms of orientation, it is perfectly parallel to its twin structure on the opposite side of Piazza del Popolo (East), which rooms extend under the foundations of Palazzo dei Priori (Priors’ Palace).
Unlike the Western complex, discovered in modern times, the Eastern one has been known since 1262, as witnessed by Gianfabrizio Atti‘s Cronaca dell’egregia città de Tode dated 16th century. Unfortunately only nine rooms, out of twelve, are accessible and visitable.
Because of the used and perfectly recognisable building construction techniques, the structure might be dated late Republican Age, and further extended for approximately one century. Both the cisterns would be filled by the water coming from the springs on top of the hill in the Rocca area, and used to be part of a monumental project for the Forum urban planning to supply water in town.
The monumental system was part of the building project dated 1st century B.C., when Todi passed from the status of municipium to the one of Splendidissima Roman colonia.