In 2012, excavations in the sanctuary continued on the fourth terrace, where the investigation was extended towards the north.

Intense building activity was documented in this area situated just outside the humid zone of the springs. The foundations of an earlier building were found in a level below “oikos I”. The foundations of its perimeter wall, made up of small stones, were very wide measuring 0.75 m. Unlike the other buildings in the sanctuary, this structure was on an east-west alignment. To date about 3.50 m of its length have been uncovered, mostly taken up by a room whose internal measurements are approximately 2.00 × 3.40 m. The room had a well-preserved and well-made cobblestone floor.
There may have been another room to the east, entered from the south. A drain covered by a tile was exposed in the external wall of the so-called antechamber, situated lower down on the slope to the west. A new trench (1/12) was opened to the north of trench 1/10, of the same length and an average width of 3.30 m. This revealed a wall that extended for its entire length. At several points, the wall showed breaks and reinforcements, despite this it is to be considered a single structural element. The stratigraphy and its construction technique, date this wall to the latest building phase on terrace 4. Another three sections of wall uncovered this year also belong to this phase.

The majority of the finds from this zone were ceramic cooking wares and banqueting wares, including Red-figure vases and good quality Gnathian ware, datable to between the second half of the 4th and the first decades of the 3rd century B.C. There were also transport and storage vessels such as amphora and pithoi, plus a repertory of miniature vases characteristic of the sanctuary of Demeter. Alongside the Demetrian type bust-protomi, depicting donors and carriers of the sacrificial basket (_kanoun_), rarer coroplastic types were also present. These included statuettes of the Dioscuri, or the squatting god “Bes” and even terracottas of juveniles in cloaks with the attributes of musical instruments or toys, known from the excavation of the so-called sacred Agora of Herakleia, which G. Pianu suggests are linked to initiatory rituals for adolescents. The faunal remains, analysed by a team from Vienna University directed by Gerhard Forstenpointner, included bones from pigs, sheep/goat and bovines, and also dog, some with butchers marks. The sample included a high percentage of pig mandibles, with a predominance of female individuals.