The archaeological investigations of 2006 undertaken in the northeastern part of the ancient city of Apollonia uncovered the remains of a portico, which due to its large size, in comparisons with the two other porticoes of the city, was named as “the large portico”. In sondage 5c, at the northeastern part of the monument, the excavations revealed the foundation corner of the lateral walls, while in sondage 5b was found the first columns of the primary line, including that of the opening row of the portico. The foundations of the columns were square with sides 2 m long; and consisted of 5 long parallelepiped limestone blocks on a base of irregular stone blocks. The foundations of the lateral walls were 1, 6 m wide and of irregular stones. The discovery of three stelae bases along the eastern part of the lateral wall, suggest the existence of a row of stelae placed opposite of the portico wall, facing the eastern entrance of the city. The layer discovered above the stylobate contained a large number of architectural fragments, probably remains from the destruction of the building, including fluted and unfluted column shafts, frames of columns bases, and a frieze with elongated beads or spirals decoration, which are probably part of a Corinthian capital. Also fragments of marble sculptures were uncovered, including that of a hand holding a pyxis. Within the northeastern corner of the portico (sondage 5c), below the foundation level, two earlier walls, which formed a rectangular corner of north-south and east-west direction were revealed. Their orientation appears to be the same as that of the _insulae_ discovered in the northern sector of the excavations. It seems that, this part of the quarter, which dates to the later Archaic period, was destroyed to make room to the construction of the large portico in the Hellenistic period. In the central part of the portico (sondage 6), the excavations exposed a squared structure (with sides 4 m long), consisting of a line of large parallelepiped stones, enclosing a fill of irregular and smaller stones. The structure was probably used as statue bases, placed at the central part of the portico. Column fragments of the Doric order were uncovered in sondage 3a, opened in front of the façade of the portico, which were not aligned in the same direction as those discovered in sondage 5b.

During the archaeological season of 2007, several new sondages were opened in the large Hellenistic portico of the ancient city of Apollonia. Sondage 5c, initially opened during the field season of 2006, was extended toward the east of the portico. The excavation exposed foundation levels of a monument built with regular limestone blocks of quadratic shape. Seven sondages were excavated to the west of the sector aiming to locate the western limits of the portico, and also understand its plan. Other structures identified during this season were: the rear wall of the portico, which was 128 m long, and run in the west-east direction (sondages 5c, 8c-f, 11 and 12); the elongated colonnade, consisting of 23 columns (sondage 8b-d, at the western edge and 5b to the east), to which a column was added at each corner (sondage 8a to the west and 5a to the east). Contrary to what was previously assumed, it is now certain that the two columns discovered do not form a second colonnade in the façade of the portico (sondage 3a, 8e and 10). Therefore, it seems likely that the portico was a one nave building with a colonnade, decorated with capitals of Doric and Corinthian orders in its façade. To the west (sondage 8g) as well as to the east (sondage 5), the rear wall of the monumental building formed right angles and then continued ahead. The wall was sustained by a north-south terracing structure, which was leveled during the construction of the portico, for the creation of a flat area of the monument’s façade. In almost all the opened sondages, the excavations revealed a great number of architectural fragments and brick columns bases, creating a thick debris layer, which might perhaps relate to the dismantling process. The foundations walls of the portico were found directly above the Hellenistic layers, and this latter, right above a layer of ceramic material of the 6th – 5th Centuries BC, suggesting the construction date of the monument at the end of the Hellenistic period.

The excavations of 2008 focused in the full discovery of the western side, and the southwestern extreme of the large Hellenistic portico of the ancient city of Apollonia. During the excavations, a badly preserved part of the foundation wall was revealed, along with a wall corner which blocked the western side of the portico. The layers above the foundation of the portico contained material of the Hellenistic and Roman periods, which seems to have arrived probably from deposits of the same time, artificially accumulated for leveling the southern area, just at the foot of hill 104. The layers found below the remains of the portico date to the Classical and Archaic periods. Traces of regular cuts were noted at the deepest levels, which are probably related with the removal of clay deposits. Some small architectural fragments were revealed during this season, such as stone wall blocks, columns bases, capitals, and the entablature of the portico. The large scale of wall destruction, along with the upper layers of debris identified in sector 10, suggest a periodic use of the area as an extraction site, robbing the remaining materials of the portico. The discovery of numerous flutings fragments of the same size, suggest that the columns shafts were dismantled for use as single blocks. These materials were reused in the construction of the nearby Medieval monastery of Saint Mary, in the houses of the village of Pojan, and perhaps even in the Ottoman buildings of the city of Berat (located some tens kilometers way from Apollonia). The discovery of a limekiln and a Doric columns shaft, in the western limits of the portico, indicates the destiny of the decorative elements after the destruction of the monument. At this phase of research it still remains ambiguous whether the numerous shaft fragments of unfluted Doric columns and fluted Ionian or probably Corinthian orders, identified during the excavations, belong to the large portico, or to another earlier apsidal structure, discovered in sector 12. Other architectonic elements discovered during the excavation included: several fragments of a sima with an anthemion, elements of a frieze containing floral motifs, probably part of monumental sima, and numerous base fragments of Attic types. The discovery of limestone columns shafts and a capital fragment with an echinus profile which dates probably around the year 500 BC, suggests the presence of a large Doric building close to the portico.

The excavations of the large Hellenistic portico continued even during the field season of 2011. In sector 15, at the northern side of the portico, the excavations identified traces of a rectangular structure, which was perhaps an auxiliary annex of the monument. The discovery of a drainage channel that collected water from the roof, directly above the terracing embankment built during the Hellenistic period with the purpose of leveling the terrain around the earlier semicircular building, might define the late 3rd or the first half of the 2nd Century BC, as a _terminus post quem_ date for the construction of the portico, or at least of one of its rearrangement phases. This also suggests that in the northern side, the wall of the portico was raised to the upper level of the terracing embankment of the Hellenistic period: no other new embankment was added during the construction of the monument. This could be one of the reasons which make it difficult to define a precise date for the construction of the portico. However, important and precise evidence for the destruction of the monument were provided by the discovery of a grave right above the foundations of the rear wall of the monument. The grave is constructed with reused Hellenistic tiles arranged in a box-like form of 0, 80 m long. The tiles are bonded with mortar at each of the grave’s corners; at its floor level and on the outer part of the contours were also paved with mortar. The skeletal remains which indicate the burial of several individuals and the associated grave goods were badly preserved. Some of the skeleton remains were found between two of the stone blocks of the foundation of the portico, suggesting that the latter was opened during the grave’s construction. The grave goods consisted mainly of: fragments of a glass bottle with fine walls, a globular body and a long neck; a bone pin with oval head; two circular pearls; two silver bars containing floral decorations; and an annular object made of iron threads. The material and the construction technique of this grave are typical of the 2nd – 3rd Centuries AD. It suggests that the destruction (as shown by the discovery of the debris layers covering the foundation levels of the portico) and the material plundering of the large Hellenistic portico took place at this time.