Darius the Great built the greatest and most glorious palace at Persepolis in the western side. This palace was named Apadana (the root name for modern "ayvan") and was used for the King of Kings' official audiences. The work began in 515 BC and was completed 30 years later, by his son Xerxes I. The palace had a grand hall in the shape of a square, each side 60m long with seventy-two columns, thirteen of which still stand on the enormous platform. Each column is 19m high with a square Taurus and plinth. The columns carried the weight of the vast and heavy ceiling. The tops of the columns were made from animal sculptures such as two headed bulls, lions and eagles. The columns were joined to each other with the help of oak and cedar beams, which were brought from Lebanon. The walls were covered with a layer of mud and stucco to a depth of 5cm, which was used for bonding, and then covered with the greenish stucco which is found throughout the palaces. At the western, northern and eastern sides of the palace there was a rectangular veranda which had twelve columns in two rows of six. At the south of the grand hall a series of rooms were built for storage. Two grand Persepolitan stairways were built, symmetrical to each other and connected to the stone foundations. To avoid the roof being eroded by rain vertical drains were built through the brick walls. In the Four Corners of Apadana, facing outwards, four towers were built.
The Walls were tiled and decorated with pictures of lions, bulls, and flowers. Darius ordered his name and the details of his empire to be written in gold and silver on plates, and to place them in covered stone boxes in the foundations under the Four Corners of the palace. Two Persepolitan style symmetrical stairways were built on the northern and eastern sides of Apadana to compensate for a difference in level. There were also two other stairways in the middle of the building. The external front views of the palace were embossed with pictures of the Immortals, the Kings' elite guards. The northern stairway was completed during Darius' reign, but the other stairway was completed much later.
