Final answer:
The three principle parts of the Persepolis site include the residential quarters, treasury, and ceremonial palaces such as the Apadana, with fortifications as an additional key feature. Persian architecture reflects a mix of influences, especially from Mesopotamian, Italic, and Hellenistic cultures, evident in the use of materials and design elements like Ionic columns and pilasters.
Step-by-step explanation:
The three principle parts of the Persepolis site are the residential quarters, the treasury, and ceremonial palaces which include structures such as the Apadana, the ceremonial hall. The fortifications forming the fourth part were also critical to the city's layout. Persepolis reflects a blend of architectural influences including elements from Mesopotamian, Italic, and Hellenistic traditions. The Mesopotamian influence is evident through the use of mud-bricks and the construction techniques involving pilasters and frescoes. The Italic influence is visible in the entry stairways akin to a pronaos, and the Hellenistic influence is seen through the Ionic order columns and the use of permanent building materials like stone.
Persian architecture notably incorporated various elements from different cultures they interacted with or conquered, making it a cross-cultural tapestry. The Mesopotamian influence is particularly significant with the sun-baked bricks, clay, pilasters, and coping with the scarcity of stone by using alternative materials. Hellenistic influences can be spotted in the ionic columns and engaged pilasters, suggesting a synthesis of Greek architectural styles that were prevalent during the Hellenistic period.