http://agathe.gr/democracy/the_boule.html
The Boule (The Senate) The Athenian legislature also included a deliberative body known as the Boule. It was made up of 500 members -- 50 from each of the 10 tribes -- who were chosen by lot and served ... Excavations have revealed the foundations of a nearly square building (23.30 m. X 23.80 m.), with a cross wall dividing the structure into a main chamber and entrance vestibule. The main room probably had five supports, although the foundations for only three have been found.
