Firuzabad is an ancient city located in the Fars Province of Iran. It was founded by King Ardashir I in the early 3rd century AD as his capital city. The city was built to symbolize Ardashir's new dynasty, the Sassanian Empire.

One of the main features of Firuzabad is its circular city plan, with the royal palace and audience hall located at the center. The circular design is believed to have been inspired by the ancient Iranian myth of the city of Arvandor, which was also said to have a circular layout.

One of the most prominent structures in Firuzabad is the Qal'eh Dokhtar, also known as the Palace of Ardashir. It is a well-preserved palace that is believed to have been used as the royal residence of Ardashir I. The palace is made of stone and features a large entrance, an audience hall, and several rooms for the king and his family.

Another significant structure in Firuzabad is the Ghal'eh-ye Kārān, or the Castle of Karan. It is a large fortress located on a nearby hilltop that was built during the Sassanian period to protect the city from invading forces. The fortress features a large gate, several towers, and underground tunnels.

Firuzabad is also known for its large irrigation system that was used to bring water from the nearby mountains to the city. The system, which includes a large dam and canals, is still in use today and provides water to the surrounding agricultural lands.