Khawarnaq
Khawarnaq was a medieval, pre-Islamic Arab castle built by the Lakhmids near their capital al-Hira. It is celebrated in the Arabic-Islamic literature and poetry as one of the "Thirty Wonders of the World". It is described in both Arabic and Persian sources, but "it seems quite impossible to distinguish clearly between historical facts and legendary accounts".
According to tradition, the Sasanian emperor Yazdegerd I is the one who requested its construction, asking the ruler of the Lakhmid kingdom (a client state of the Sasanians), Al-Nu'man I, to carry out the construction in the early fifth century, and for it to be a place for the young Sasanian prince Bahram V to be able to grow up in. Later, during Abbasid times, the castle was enlarged.
The design of Khawarnaq was due to the legendary architect Senemar. After completing the design, the architect was killed, to prevent him from designing a similar castle for another person.