The mystery is hidden under a layer of sand: archaeologists have discovered a rare find.

The ruins of a 1500-year-old fortress have been found in Iran.

In Khorasan, eastern Iran, archaeologists have discovered a rare find — an almost circular adobe building with six towers, erected in the 6th century BC .

This discovery took place near the city of Birjand, located in South Khorasan.

Excavations in this area, known as Tappe Tahchar-Abad, began in 2009 and are among the few ongoing studies in the region. In eastern Iran, archaeological sites are rare, and only two of them have been discovered before: Dahaneh-i Golaman in Sistan south of Khorasan and Tappe Rivi in northern Khorasan.

Tappe Tahchar Abad is located on a barren plain, near Birjand, on the edge of a semi-conical hill. The dimensions of this building are impressive: its base diameter is 42 meters and its height reaches 4 meters. Surrounded by a moat about 11 meters wide with a canal to the northeast, it represents a unique architectural feature.

After four seasons of excavation, the remains of an almost circular adobe building with a diameter of 18 meters, with six massive towers and walls up to three meters high, were discovered. The building was found covered in sand and its filling took place in two stages, indicating careful planning of its structure.

Interestingly , archaeologists claim that the building was erected during the reign of the Achaemenids, the duration of which is about 200 years (550−330 BC).

This is a period in Iran's history when the Achaemenid Empire ruled vast territories stretching from the Syr Darya River to Egypt.

Despite the difficulty in identifying materials from the Achaemenid period due to their similarity to earlier periods, archaeologists have been able to date the pottery found at the site and confirm its belonging to the Achaemenid periods and Parthian rule. This discovery promises to shed new light on the history of the region and its significance in antiquity.