This historical complex, extending over more than 10 kilometers, was the only known winter residence of the Ghaznavid and Ghurid sultans—two dynasties that ruled a vast region, including present-day Afghanistan, between the 10th and 13th centuries CE and played a significant role in the expansion of Islamic art into northern India.
During the Seljuk period in the 11th and 12th centuries, the Bost citadel was recognized as an important point along the communication route between Khorasan (the northeastern Iranian plateau) and Ghazni in the mountains of Afghanistan. The ancient Qala-e Bost lies about 10 kilometers south of the modern city of Lashkargah, in the plains of Afghanistan, surrounded by ruins.
Some researchers attribute the name “Bost” to early Zoroastrian hymns in the Avesta. Traditions such as Nowruz and ceremonies related to the spring equinox were also held in this region around 3,000 years ago. The name appears in the list of Achaemenid cities and is also mentioned in early medieval reports by missionaries, poets, merchants, and military chroniclers. Although these sources are sometimes vague, evidence suggests that the Bost citadel was an important and well-known region even before the Christian era, and that it was captured around 661 BCE by the early Arab conquerors.
In the 11th century, Bost flourished as the winter capital of the Ghaznavids, a Muslim dynasty that ruled Afghanistan and Punjab for over two centuries. In this context, Sultan Mahmud of Ghazni, the most prominent ruler of this dynasty, played a key role in expanding Ghaznavid power through numerous military campaigns into the Punjab region. By plundering wealthy cities in India, he transferred substantial resources to Ghazni, turning the city into one of the major centers of Islamic culture. Among the notable works attributed to him is a magnificent marble mosque that still survives today. During this period, the Bost citadel also benefited from this prosperity and splendor.
This historical structure, with a history of more than 3,000 years, has witnessed the rise and fall of numerous empires and still stands today. The complex consists of two main features: first, the Arch of Qala-e Bost, famous for its 25-meter decorative arch built in the 11th century, which is recognized as a national symbol and a historical treasure of Afghanistan. This emblem was once used as an official seal and even appeared on 10,000 afghani banknotes, as well as on 100 afghani banknotes issued in 1993.
The second major feature of this complex is a spiral staircase inside a well, which, with a depth of 45 meters and a diameter of 6 meters, is considered one of its unique architectural elements. In this structure, three of the four circular chambers are connected to the shaft through successive arches. The building originally had eight floors, five of which remain today, while the other three underground levels have been lost.