Archaeologists in the eastern Iraqi province of Diyala have uncovered underground passages in their excavations that appear to be secret passageways leading to a palace from the Sassanid era, according to the official Iraqi News Agency.

Archaeologists say the site was found within the city of Miqdadiyah in the northeastern part of Diyala province and estimate that it was built more than 1,400 years ago, where it had been repeatedly invaded by different groups.

According to archaeologists, this city was probably the summer residence of Khosrow Parviz, the Sassanid king.

Ahmad Abdul Jabbar Khums, head of Diyala archeology, said the findings show that “the city was an important economic and military center, and since it was built of clay, limestone, and mud, it was probably the residence of royal princes and families.” Life in the city apparently continued after the Arab invasion, but the inner courtyard of the palace was not accessed and even a mosque was built outside the mansion’s grounds.

The satellite images, along with surveys taken over a whole year to conduct and analyze the site, show different locations including a place where the Sassanid king likely spent a great deal of time, with wide corridors to receive guests and visitors.