Ali Shah served as vizier under the Ilkhanate rulers Oljeitu and Abu Sa'id in the early 14th century. His grand mosque compound was organized around four iwans and oriented toward Mecca. The marble-paved courtyard measured 286 meters wide by 229 meters long, entered through an elaborate gateway called a pishtaq. Inside, an octagonal fountain spouted water from four stone lions beneath surrounding trees. The main iwan barrel vault -- 30.5 meters wide, 48 meters deep, with a total distance of 65.5 meters from portal to mihrab -- was the heart of the project. The total height exceeded 45.7 meters: a 24-meter base supporting a vault that soared an additional 21.7 meters. But the engineering of a roofless span that large, without supporting pillars, proved beyond the capabilities of the age. The vault fell. The mausoleum was never completed. What survived were the massive brick walls -- thick, plain, and virtually indestructible.

For centuries, the ruined compound stood largely unchanged. Then the Russo-Persian Wars arrived. Between the first war of 1804-1813 and the second in 1826-1828, the Arg was hastily converted into a military installation. A cannon foundry was built within its walls. Barracks housed troops. A small palace was erected for commanders. Samson Makintsev, a Qajar general of Russian origin known as Samson Khan, lived inside the citadel with his wife, the daughter of Prince Aleksandre of Georgia. The French traveler Eugene Flandin sketched the ruins in 1840, capturing the strange beauty of a medieval mosque transformed into a military compound. Jean Chardin had drawn the remnants even earlier, in 1673, documenting what was already ancient.

In 1911, Russian troops invaded Tabriz and shelled the Arg in their opening attacks. Once they captured the city, they repurposed the citadel as their central command center -- the same transformation the Persians had made a century earlier. During the Russian occupation, careless handling of artillery pieces set fire to parts of the structure. Photographs from the period show the Russian flag flying atop the Arg and smoke rising from its interior. The building that had survived earthquakes and the collapse of its own roof now bore the scars of modern warfare. A US flag also flew nearby at the American consulate during the Persian Constitutional Revolution, a reminder of how many powers have circled this single structure.

During the Pahlavi era, authorities attempted to strip away 19th-century Qajar additions and restore the Arg to its original Ilkhanid form. The effort backfired. In tearing out what they considered later accretions, workers unwittingly destroyed much of the original Ilkhanid and Safavid material as well. Only a small section of the rear qibla wall, containing the mihrab with its three relieving arches, survived intact. The southern grounds were turned into the Mellat Garden -- the People's Park -- before the 1979 revolution. Then came the 1990s renovation. The remaining Qajar-era elements were demolished. A large new mosque was constructed directly adjacent to the citadel, its foundations destroying the underground remains of the original Arg that scholars had hoped to use for reconstruction. The main prayer hall of Ali Shah's 700-year-old mosque was paved over and turned into a parking lot.

Today, the Arg of Tabriz is essentially one wall. It was added to the Iran National Heritage List in 1932, but protection has not prevented continued degradation. The new mosque built beside it visually overwhelms the ancient structure. The parking lot covers sacred ground. Yet that surviving wall -- massive, plain, brick -- remains one of the most remarkable architectural fragments in Iran. It is all that endures of a vizier's ambition to surpass the greatest vault in history. The mihrab is still visible at the center of the qibla wall, flanked by two high windows. The relieving arches still carry the weight of seven centuries. From above, the Arg appears as a dark rectangular mass amid Tabriz's dense urban fabric, dwarfed by modern construction but unmistakable in its antiquity. It stands as a monument not to what was built, but to what refused to fall.