Naubakht was a famous Zoroastrian astrologer and architect who worked at the Court of the Abbasid Caliph al Mansur. In 762 AD, he designed the city of Baghdad, which means "gift of God" in Persian. Naubakht designed the city as a circle. So, Baghdad was known as the "Round City."
Naubakht's design was based on the Sassanian city of Gur which was later known as Firuzabad. The picture on the right shows the aerial view of the ancient Gur.