Its most flourishing period was during the 3rd century BCE and the first half of the 2nd century BCE (until 146 BCE), when Oropos was part of the Boeotian League. From the early 4th century BCE until 338 BCE (the Battle of Chaeronea), the Amphiareion began organizing formally, and its fame spread across Greece. On the left bank of the sanctuary lie the official structures: the temple, altar, stoa, and theater. Five marble thrones around the orchestra, dated to the 1st century BCE, were reserved for priests and dignitaries attending performances. At the spot of the final pedestal, walls of a small 4th-century BCE temple still stand to considerable height.