Persian columns or Persepolitan columns are the distinctive form of column developed in the Achaemenid architecture of ancient Persia, probably beginning shortly before 500 BCE. They are mainly known from Persepolis, where the massive main columns have a base, fluted shaft, and a double-animal capital, most with bulls. Achaemenid palaces had enormous hypostyle halls called apadana, which were supported inside by several rows of columns. The Throne Hall or Hall of a Hundred Columns at Persepolis, measuring 70 x 70 metres was built by the Achaemenid king Artaxerxes I. The Apadana hall is even larger. These often included a throne for the king and were used for grand ceremonial assemblies; the largest at Persepolis and Susa could fit ten thousand people at a time.