Persepolis
Darius I built the greatest palace at Persepolis on the western side of platform. This palace was called the "Apadana". The King of Kings used it for official audiences. The work began in 518 BC, and his son, Xerxes I, completed it 30 years later. The palace had a grand hall in the shape of a square, each side long with seventy-two columns, thirteen of which still stand on the enormous platform. Each column is high with a square Taurus (bull) 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 lions, eagles, human beings and cows (cows were symbols of fertility and abundance in ancient Iran). 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 5 cm, which was used for bonding, and then covered with the greenish stucco which is found throughout the palaces.
Persepolis
After invading Achaemenid Persia in 330 BC, Alexander the Great sent the main force of his army to Persepolis by the Royal Road. He stormed the "Persian Gates", a pass through modern-day Zagros Mountains. There Ariobarzanes of Persis successfully ambushed Alexander the Great's army, inflicting heavy casualties. After being held off for 30 days, Alexander the Great outflanked and destroyed the defenders. Ariobarzanes himself was killed either during the battle or during the retreat to Persepolis. Some sources indicate that the Persians were betrayed by a captured tribal chief who showed the Macedonians an alternate path that allowed them to outflank Ariobarzanes in a reversal of Thermopylae. After several months, Alexander allowed his troops to loot Persepolis.
Around that time, a fire burned "the palaces" or "the palace". Scholars agree that this event, described in historic sources, occurred at the ruins that have been now re-identified as Persepolis. From Stolze's investigations, it appears that at least one of these, the castle built by Xerxes I, bears traces of having been destroyed by fire. The locality described by Diodorus Siculus after Cleitarchus corresponds in important particulars with the historic Persepolis, for example, in being supported by the mountain on the east.