Building 1 is the main stoa of Kallithea’s central public zone. The foundation walls are clearly visible, consisting of large rectangular limestone blocks of similar size and shape to those of the city walls, and were already included in Stählin’s general map of the site from the early 20th century CE. The building is rectangular in shape and measures ca. 50 x 15 m. As the building lies on the north slope of the hill, the foundation height varies considerably from 1.2 m in the north to 0.2 m in the south so as to provide a long, level platform.
Initial survey of the stoa was carried out in 2004 and 2005 when the visible architecture was drawn and mapped. Excavations began in 2008 by the team from the 15th Ephorate in Larissa, when the first 13 m of the western side were investigated. This work was dictated by the fact that the building is impressive, with well-preserved architectural members lying close to the modern surface level. It is hoped that its excavation will elucidate factors of social and economic organization of the city.
While work is ongoing, excavation to date has already clarified the overall structure of the stoa. Its northern and western foundation walls, both built with large exterior blocks faced internally with smaller unworked stones, serve as retaining walls of the broader agora area. A layer of red clay soil mixed with limestone pebbles, stone chips, and a few sherds forms the floor level. Alongside and in contact with the lower part of the western wall of the building was a foundation offering of cattle bones within a coarse-ware two-handed bowl. Within the stoa, a row of limestone bases running E-W are supports for an internal colonnade of unfluted sandstone columns, parts of which were found fallen on the floor. The bases are square with slight round protrusions. Two possible stele bases have been found both inside and surrounding the stoa.