The Tholos (dome), one of the most significant buildings of the Ancient Agora, is located south of the Metroon and the New Bouleuterion. It is a circular building, also referred to as ‘Skias’ (Shadow), as its shape resembles a sciadium, meaning a parasol or a wide-brimmed hat.
The spacious circular building, constructed around 470 BCE, has a diameter of about 18 m. with its entrance located on the eastern side. Inside, a circular arrangement of six marble Ionic columns provided support for the conical roof, which was covered with large rhombus-shaped clay tiles. It is believed that the roof had an opening at the top (opaion) for ventilation, as remains of an altar have been uncovered inside. However, other scholars believe that the roof was closed and that the sacrifices made at the altar would have been symbolic ones, without the use of fire. Around the building there was a peribolos, while two small rooms to the north have been interpreted as a storeroom and a kitchen.
According to Aristotle, the Tholos served as the seat of the Prytaneis (executors) of the Boule (Council of Five Hundred). As the Boule was a large, and therefore dysfunctional body, the institution of the prytany had been established to facilitate a quicker and more efficient resolution of issues.
The term Prytaneia referred to the period during which the fifty representatives from each of the ten tribes of Attica presided over the sessions of the Council of Five Hundred, following the constitutional reforms of Cleisthenes at the end of the 6th century BCE. Each prytaneia lasted 35-36 days (1/10 of the year) and the order in which the tribes would exercise it was determined by lot. The presiding tribe was called the prytanevousa and its members were called prytaneis. A president was also appointed by lot, known as epistates (steward) of the prytaneis, essentially serving as the head of state, somewhat akin to the modern-day President of the Republic, for one day. The epistates of the prytaneis was also responsible for safeguarding the keys of the sanctuaries, the public records, the state seal, as well as the standards of measures and weights for overseeing commercial activities. The prytaneis were compensated by the state for their services with a daily wage of six obols, while the epistates of the prytaneis received 10 obols.
In the Tholos, the prytaneis would dine, and 1/3 of them stayed there overnight to facilitate prompt decision-making in case of emergencies. The institution of the prytaneia held great significance and, during the 4th century BCE, the practice of awarding praise for the presiding tribe that had executed its term most successfully was established.
The building likely suffered damage during Sulla’s invasion of Athens in 86 BCE and underwent renovation in the 1st century CE: a monumental propylon, featuring four Ionic columns, was added to the eastern side of the structure, and a fountain was constructed to the west. Around the same time or slightly later, during the period of the city’s beautification by Emperor Hadrian, the floor was also paved. The Tholos, along with the entire western part of the Ancient Agora, was destroyed during the raid of the Heruli in 267 CE.
