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The Achaemenid circular structure discovered at Tappe Takhcar-Abad	Source: Mohsen Dana et al. / Antiquity

2,500-Year-Old Achaemenid Marvel Excavated in Iran


While excavating in a lightly explored eastern region of their home country, a team of Iranian archaeologists unearthed the remains of a solid circular adobe structure that featured six separate towers. The ancient structure, which was constructed on a man-made mound known as Tappe Takhchar-Abad, has been dated to the sixth century BC, during the era of the legendary Achaemenid Empire. This means the building and its towers are at least 2,500 years old.

The astonishing fortress was discovered near the city of Birjand in the province of South Khorasan in northeast Iran. It is an architectural relic from ancient times when Iran was a center of remarkable civilizations, showcasing the ingenuity of Achaemenid builders and their mastery of adobe construction techniques during the period of the Achaemenid Empire, which thrived from 550 to 330 BC.

“The evidence of pottery, building plan and absolute dating indicate that the Takhchar Abad building was constructed in the late Iron Age/Achaemenid period,” the Iranian archaeologists wrote in an article published in Antiquity. “This building was abandoned  c. 500–400 BC, until the Parthian period (second and third centuries AD) when it was reoccupied; finally, it was filled and covered during the third–fourth centuries AD.”

Excavations commenced in the Khorasan region in 2009 and have persisted to the present day. However, because of remote and barren nature of the area only four excavation seasons have ever been completed. The latest Achaemenid find represents perhaps the most dramatic discovery to be made at this long-neglected location. 

Aerial view of Tappe Takhchar-Abads depicting 1. The village, 2. the Tappe and ditch surrounding it and 3. The diversion dam. (Mohsen Dana et al. / Antiquity)

Aerial view of Tappe Takhchar-Abads depicting 1. The village, 2. the Tappe and ditch surrounding it and 3. The diversion dam. (Mohsen Dana et al. / Antiquity)

Hidden Secrets of Achaemenid Architecture Revealed

The towers and accompanying structure occupy the apex of the elevated formation known Tappe Takhchar-Abad, which sits on a deserted plain on the outskirts of Birjand. Tappe Takhchar-Abad is a semi-cone-shaped mound that has a diameter of 138 feet (42 meters) and a height of 13 feet (four meters). Its Achaemenid builders surrounded the site with a 36-foot (11-meter) wide trench that was supplied with water from a nearby reservoir, so it could function as a protective moat.

Archaeologists unearthed the circular building, which was made from adobe and pisé (rammed earth), during the most recent excavation season. When they were finished digging what they’d revealed was a structure with a diameter of 59 feet (18 meters) that featured six solid towers and walls that were as high as 10 feet (3 meters) at their tallest points.

Interestingly, the building had not been covered by the forces of nature but had instead been intentionally buried and filled with sand approximately 1,700 years ago. The burying process had taken place in two stages, as tests showed the building was filled up to a height of six feet (almost two meters) with alternating layers of brick, sand and stones.

The Achaemenid circular structure discovered at Tappe Takhcar-Abad, with its six towers (1-6), as seen from the air. (Mohsen Dana et al. / Antiquity)

The Achaemenid circular structure discovered at Tappe Takhcar-Abad, with its six towers (1-6), as seen from the air. (Mohsen Dana et al. / Antiquity)

The latest digs at Tappe Takhchar-Abad revealed that after the structure had been filled and covered the first time, new buildings were constructed directly over it. This would have taken place during the latter stages of the Parthian period (247 BC – 224 AD), when the lands of eastern Iran were controlled by the Parthian Empire.

Circular structures have been found in the surrounding region before, and traditionally these structures have always been credited to the Parthians. But the latest evidence shows that the Achaemenids built older versions of these round buildings, presumably creating the model that the Parthians later followed.

However, this architectural style didn’t actually originate in the Achaemenid culture. Even older circular structures have been discovered at several sites excavated in Bactria, an ancient Iranian state to the east of Greater Khorasan that included the lands of modern-day Afghanistan, Tajikistan and Uzbekistan.

In fact the building on Tappe Takhchar-Abad closely resembles an Iron Age/Achaemenid-period circular structure with towers known as Garry Kyariz I, which is located 42 miles (67 kilometers) northwest of Ashgabat, Turkmenistan, on lands that would have been adjacent to Bactrian territory in ancient times.

“The construction of circular buildings and sites is an architectural tradition of the late Iron Age/Achaemenid period in Greater Khorasan, apparently originating from Bactria where the majority of such sites are found,” the study authors wrote, confirming the importation of this building style from the east. 

The adobe structure at the ancient Achaemenid structure discovered in Iran. (Mohsen Dana et al. / Antiquity)

The adobe structure at the ancient Achaemenid structure discovered in Iran. (Mohsen Dana et al. / Antiquity)

Rediscovering the Mightiest Empires of the Ancient Middle East

At the height of its power, the Achaemenid Empire included land stretching from the River Syr Darya in central Asia all the way to Egypt in the far west. Most of what is known about the Achaemenid culture comes from excavations in southwest Iran, where the empire was based. Nevertheless, up to now archaeological excavations have been few and far between in the Greater Khorasan region of eastern Iran, even though it is known that the Achaemenids had an active and robust presence in this area.

This is why the unearthing of the circular structure and its towers in South Khorasan is generating so much interest in the archaeological community. The existence of the trench surrounding it makes it clear that this was some kind of fortress or guard post, which could have kept a watch out for invaders who might have threatened the village of Takhchar-Abad.

In addition to what was discovered at Tappe Takhchar-Abad, recent excavations inside the village of Takhchar-Abad resulted in the recovery of a diverse collection of pottery pieces. Some of these have been linked to the Late Iron Age and the early Achaemenid period (from the seventh through the sixth centuries BC), while the remainder came from Parthian settlers who lived in the village several hundred years later. This has helped the researchers pin down the timeline of when the village was occupied, and by whom.

When excavations resume at Takhchar-Abad, Iranian archaeologists will continue their search for artifacts that shed light on the cultural, social, economic and spiritual practices of the Achaemenids and the Parthians, who represented two of the most powerful and influential empires to arise in the ancient Middle East.

Top image: The Achaemenid circular structure discovered at Tappe Takhcar-Abad. Source: Mohsen Dana et al. / Antiquity

By Nathan Falde

Nathan Falde's picture


Nathan Falde graduated from American Public University in 2010 with a Bachelors Degree in History, and has a long-standing fascination with ancient history, historical mysteries, mythology, astronomy and esoteric topics of all types. He is a full-time freelance writer from... Read More

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