To create the level terrace, any depressions that were present were filled up with soil and heavy rocks. Darius ordered the construction of Apadana Palace and the Debating hall (Tripylon or the three-gated hall), the main imperial Treasury and its surroundings, which were completed at the time of the reign of his son, King Xerxes I.
The designers were greatly influenced by the Mesopotamians in their construction, and when a significant portion of the city was completed, Darius declared it the new capital of Persia, replacing Pasargadae.
The other three sides are formed by retaining walls, which vary in height with the slope of the ground.
The earliest remains of Persepolis date back to 515 BC.
It exemplifies the Achaemenid style of architecture.
UNESCO declared the ruins of Persepolis a World Heritage Site in 1979.
The site includes a 125,000 square meter terrace, partly artificially constructed and partly cut out of a mountain, with its east side leaning on Rahmet Mountain.
Persepolis Rising is the upcoming seventh novel in The Expanse series.