Between 2006 and 2009 excavations took place in the piazza of the sanctuary of Heracles at Alba Fucens, a Latin colony founded in 307 B.C. The aim was to investigate the earliest phases of the building whose 1st century B.C. plan is already known. In 2011, research in the southernmost sector of the piazza was completed. A large amount of material datable to the 3rd century B.C. was recovered; however, there was no certain evidence for a building of the same date as the structures that emerged were part of the original interventions to fill the central depression prior to the construction of the monumental colonnaded space. A final _sondage_, opened near the _sacellum_ in which the colossal statue of Heracles Epitrapezios was found, revealed the presence of a large circular cistern, situated immediately below the abandonment layers in the piazza (fig. 1). A similar, but smaller structure had already been identified by Belgian excavators at the foot of the steps leading up to the _sacellum_. However, this had only been partially investigated. The large cistern (diam. 4,13m), discovered in 2011, was excavated to a depth of c. 5 m. The results from investigations undertaken by the National Institute of Geophysics and Volcanology using electric tomography suggested that the basin was about 6 m deep. Useful evidence was provided by the presence of other channels within the sanctuary piazza, forming part of a complex underground water supply system. The cistern was built in polygonal masonry and the upper border had been rebuilt several times. The upper layer of the fill, mainly made up of tegulae and stone in particular _cubilia_ from the sanctuary’s walls, was removed. This revealed column drums, bases and capitals, which formed the last substantial layer sealing the cistern (fig. 2). The gradual removal of this material showed that it was a deliberate accumulation of architectural elements, mixed with numerous fragments of pottery, glass, and marble. The particular characteristics of the damp environment meant that several timber elements were preserved, including four long beams, still _in situ_, that must have been part of the structure supporting the covering at the level of the piazza (fig. 3). Various parts of marble and bronze statues were recovered at various depths. An intact portrait bust of an old man with strong, realistic features, datable to the first half of the 1st century B.C., was also found (fig. 4). The cistern was filled in a late period, the first decades of the 6th century A.D., date given by the latest pottery found. Most of the material recovered derived from the destruction of the sanctuary of Heracles, which occurred between the end of the 5th and the early 6th century A.D. following a severe earthquake whose effects were also felt in Rome, as recorded by the pair of inscriptions on the Colosseum. In 2012, the emptying of the structure will be completed and a number of soundings will be opened in the surrounding area, in order to determine the stratigraphic relationships and gain an understanding of the cistern’s construction phases and chronology, and its relationship with the sanctuary’s phases.