TEHRAN -- At the southern edge of the Iranian high plateau near the Pakistani border, the hilltop citadel of Arg-e Bam marks the Silk Road. According to legend, this earthen architecture city owes its existence to a magic worm.
In the epic poem, Shahnameh, by Persian poet Ferdowsi, a girl was spinning cotton when she discovered a worm in her apple. As it continued to eat and grow, it secreted a delicate thread that brought great wealth to her father, Haftvad, who fortified the city in order to protect its magic. According to historian and geographer Hamdollāh Mostowfi, when an invading conqueror stormed the citadel and pierced the worm with a metal rod, “the Worm of Haftvad burst, and for which reason the place took the name of Bam (meaning burst).”
The magic worm of Ferdowsi’s epic was likely a silkworm. Built during the 6th to 4th centuries B.C. at the crossroads of important trade routes, Bam earned its reputation for the production of silk and cotton garments, which were reportedly so fine they found their way into the closets of kings.
Its strategic location in the desert basin between the Kafut Mountains to the north and the Jebal-e Barez Mountains in the south was essential to its prosperity. Alpine rivers once flowed into Bam through an ingenious series of qanāts, underground irrigation canals, which transformed the city into a desert oasis capable of sustaining agriculture. The citadel’s vaulted and domes structures are characteristic of a medieval fortified city, and were built using chineh (mud layers) and khesht (sun-dried mud brick).
By the 19th century, most of Bam’s inhabitants moved to settlements outside the citadel, but its buildings and mosques were continuously used for education, religious practices, and cultural celebrations like Nowruz, the Persian new year, through the 21st century. 
In the early morning hours of December 26, 2003, a 6.6 magnitude earthquake along the Bam Seismic Fault devastated the region. More than 30,000 died, tens of thousands were injured, and an estimated hundred thousand left homeless. Much of Arg-e Bam’s defensive walls and Governor’s Quarters were reduced to debris, however the qanāts and foundations of the citadel remained intact, revealing new layers of history to archeologists.
 UNESCO prepared a comprehensive reconstruction plan spanning 2008 to 2017 to repair the city using the original earthen architecture techniques and materials. In 2013 it was removed from the List of World Heritage in Danger and as of 2022 more than 90 percent had been restored.