Thucydides describes all the work that followed and refers to its progress in detail. It begins with the construction of the circular wall(6.98.2: They walled the circle), they proceed first, building the northern wall(6.99.1: They walled the northern wall of the circle), then beginning the southern wall(6.101.1: From the circle the Athenians started to wall the cliff above the swamp), then completing it(6.103.1: Beginning from Epipolae and the sheer area they started to wall up to the sea…).