The 2015 campaign of the Onchestos Excavation Project was conducted from June 8 to July 18. The team’s main focus at Site A was the annex to the north of the large Archaic hall. Here, in addition to four trenches from 2014, five new trenches were opened to reveal the structure’s plan. The annex had its own separate south wall, laid out on an east-west axis and made of rectangular blocks of limestone. Its west wall continued for nearly 8 meters on the same axis as the Archaic hall’s west wall. The north wall of the annex extended diagonally on a west-southeast axis with a door opening at its center. These discoveries revealed that the “annex” was a rather large closed room.

At Site B, the excavation prioritized the eastern part of the site in which the geophysical survey of 2014 had indicated the existence of previously unknown structures. First, a grid of 4 x 4 m squares was laid over the entire site. The eleven trenches opened in 2015 shed light on an area, which had not been investigated during the previous short rescue excavations. The architectural remains unearthed confirmed the existence of the large rectangular structure seen in the geophysical survey. Moreover, several stone blocks forming an arch verified the presence of a circular structure (with a diameter of nearly 40 meters) partially overlapping the rectangular one; future campaigns will illuminate the exact architectural layout of this area and the stratigraphy of both edifices.

The annex at Site A was abundant in small finds that are in keeping with the nature of the portable finds unearthed in the same area during the 2014 campaign and corroborating that this structure functioned as a storage facility housing the votive offerings to the sanctuary. Meanwhile, with the opening of several new trenches at Site B, the amount of small finds increased considerably. Architectural material included large terracotta roof tiles, several fragments of a painted terracotta sima, and limestone column fragments, all of which provided clues about the elevation of the rectangular structure. Small finds comprised a large amount of diagnostic pottery and numerous metal objects from both sites. Several coins, including those from Chalkis and Macedonia (Philip II) enriched the already impressive numismatic evidence from the site.