The Taq Kasra is now all that remains above ground of a city that was, for seven centuries—from the 2nd century BCE to the 7th century CE—the main capital of the successor dynasties of the Persian empire: Parthians and Sassanids.

The structure left today was the main portico of the audience hall of the Sassanids who maintained the same site chosen by the Parthians and for the same reason, namely proximity to the Roman Empire, whose expansionist aims could be better contained at the point of contact.

Taq Kasra was inscribed in the UNESCO World Heritage Tentative List on July 7, 2000 CE, in the Cultural category.

circa 300-600 CE

Sasanian Era
The exact time of construction is not known with certainty. Some historians believe the founder is Shapour I who ruled Persia from 242 to 272 CE and some other believe that construction possibly began during the reign of Anushiruwan the Just (Khosrow I) after a campaign against the Byzantines in 540 CE.

Arab-Muslim Period
The structure was captured by the Arabs during the conquest of Persia in CE 637. They then used it as a mosque for a while until the area was gradually abandoned. During the founding of Baghdad (762–767 CE), the Abbasid Caliph al-Mansur intended to completely demolish the palace to use its bricks for his new capital. He was famously talked out of it by his Persian advisor, Khalid the Barmecide. Khalid argued that leaving the magnificent arch standing served as a physical testament to the ultimate triumph of Islam over the mighty Sasanian Empire.

Taq Kasra is the subject of an even more famous 9th-century Arabic poem (Siniyyat al-Buhturi) by the acclaimed Abbasid court poet al-Buhturi. His vivid description of the fading murals and haunting majesty of the arch remains a masterpiece of classical Arabic literature.

In the early 10th century, the Abbasid caliph al-Muktafi dug up the ruins of the palace to reuse its bricks in the construction of the Taj Palace in Baghdad.

The monument is also the subject of a poem by Khaqani, who visited the ruins in the 12th century CE.

Victorian Era
In 1851 CE French artist Eugène Flandin visited and studied the structure with Pascal Coste who remarked "the Romans had nothing similar or of the type". In 1888 CE, a serious flood demolished the greater part of the edifice. Later on the northern (right) edifice was reconstructed during the restoration program by Saddam Hussain.

Modern Era
The monument was in the process of being rebuilt by Saddam Hussein's government in the course of the 1980s, when the fallen northern wing was partially rebuilt. All works, however, stopped after the 1991 Persian Gulf War. From 2004 to 2008 the Iraqi government cooperated with the University of Chicago's Diyala Project to restore the site at a cost of $100,000. The Ministry of Culture also invited a Czech company, Avers, to restore the site. This restoration was completed in 2017 CE.

circa 300-600 CE

Central Iwan
The arched iwan hall, open on the facade side, was about 37 meters high 26 meters across and 50 meters long, the largest man-made, free standing vault constructed until modern times. The arch (inspect) was part of the imperial palace complex. The throne room—presumably under or behind the arch—was more than 30 meters (110 feet) high and covered an area 24 meters (80 feet) wide by 48 meters (160 feet) long. The top of the arch is about 1 meter thick while the walls at the base are up to 7 meters thick. This was done to reduce the risk of structural collapse under its own weight, the vault drastically tapers as it ascends. To further lighten the weight pressing down on the crown, builders hollowed out sections of the masonry above the vault, embedding rows of empty terracotta jars and clay pipes within the mortar to create structural voids.

It is the largest vault ever constructed in the world. The catenary arch was built without centring (temporary structure upon which the stones of an arch or vault are laid during construction). In order to make this possible a number of techniques were used. The bricks were laid about 18 degrees from the vertical which allowed them to be partially supported by the rear wall during construction. The quick drying cement used as mortar allowed the fresh bricks to be quickly supported by those that were previously laid.

circa 300-600 CE

Facade
The grand archway was flanked by a massive, multi-tiered facade that originally stood over 43 meters high. It seems to have been heavily influenced by Roman architecture, featuring rows of blind arcades, decorative niches, and paired engaged columns stacked in five distinct tiers. However, this was purely decorative and "non-structural"—the facade did not hold up the arch, but rather framed it.

While the monumental facade presented an illusion of absolute axial symmetry to an observer situated within the primary courtyard, empirical architectural surveys indicate intentional deviations in the spatial configuration of the flanking wings. Master builders incorporated subtle dimensional variances between the northern and southern sectors; these micro-adjustments served a dual purpose, functioning both as a form of entasis to counteract forced perspective distortions and as an adaptive engineering stratagem to accommodate the differential settlement inherent to the unstable, alluvial soil of the Mesopotamian river basin.

circa 300-600 CE

Interior
The bare brick seen today is a skeleton. Historically, the interior walls were covered in thick white stucco, deeply carved with geometric, floral, and royal reliefs. Elaborate, multi-colored glass mosaics depicting battle scenes, hunts, and court life lined the upper upper reaches, while the floor was famously covered by the Spring of Khosrow carpet (Baharestan Carpet)—a legendary, now lost, textile woven with gold, silver, silk, and precious gems representing a royal garden in full bloom.

circa 300-600 CE

National Museum of Iran
The National Museum of Iran, designed by French architect André Godard and completed in 1937, functions as a programmatic manifestation of Pahlavi-era state nationalism through deliberate historicist citation. The building’s facade centers on a monumental, deep-set brick iwan that directly replicates the scale, parabolic profile, and structural rhythm of the 6th-century Taq Kasra, the imperial palace of the Sasanian Empire at Ctesiphon. Godard rejected the Islamic-era tilework characteristic of contemporary Iranian public buildings, opting instead for exposed dark-red brick masonry to visually align the modern institution with pre-Islamic Persian antiquity. This architectural borrowing serves a dual ideological purpose: it legitimizes the modern state by physically anchoring it to Iran’s imperial past while providing a monumentally secure, culturally resonant repository for the nation's archaeological heritage. The integration of ancient Sasanian forms with modern 1930s reinforced concrete interiors demonstrates a calculated synthesis of ancestral identity and European-influenced modernization.