Ctesiphon
Ctesiphon (in Parthian and Pahlavi: Tyspwn or Tisfun; in Persian: تيسفون, Tisfun; in Arabic: المدائن, al-Madāʾin, "the cities") was a city and capital of the Parthian and Sassanid empires. It was located on the banks of the Tigris River and was soon abandoned after the founding of Baghdad. It became one of the most important cities in the ancient region of Mesopotamia.
It was formed as a peripheral neighborhood of the Greek colony of Seleucia del Tigris, which it ended up absorbing and creating a new city, which is called by some authors as Seleucia-Ctesiphon. Later, around ancient Ctesiphon and other settlements, the city of Madain would be founded. Currently, part of the surviving remains are located within the Iraqi city of Salman Pak.
Etymology
In the Book of Ezra of the Hebrew Bible it is mentioned for the first time with the name Kasfia or Casphia, a word derived from the ethnic name Cas and cognate of Caspian and Quazvi.
Ctesiphon, also appears transliterated with other spellings such as Ctesiphon, Ctesiphon or Tesiphon (name derived from the Persian Tisfun) since the II a. C.
History

The first settlement in the area was the Greek colony of Seleucia, founded in 312 BC. C. by Seleucus I Nicátor—one of the generals of King Alexander the Great—on the western bank of the Tigris, at a strategic point due to its proximity to the Silk Road. The growth of the city meant that by the year 221 BC. C. there was already a new neighborhood on the western bank of the Tigris.
In the year 147 BC. C. the Parthians attacked Seleucia for the first time and it was definitively conquered in 141 BC. C. However, the births in the year 129 BC. C. decided that on the eastern bank of the Tigris and just opposite Seleucia, they were going to locate their new capital, right where the suburb that was already known as Ctesiphon was located.
In the year 115 BC. C., fourteen years later, the new capital was practically urbanized and the Parthian kings moved their court to the city, which grew and expanded until it merged with the old Greek colony.

During the 1st century BC. C., the city Seleucia-Ctesiphon was a cosmopolitan cultural mix with, among others, Parthians, Persians, Iranians, Babylonians, Greeks, Jews, Assyrians, Arabs or Turks.
In the Babylonian Antiquity was the metropolis of Assyria; but the metropolis is now Seleuceia, that is, Seleucia of the Tigris, as it is called. Nearby there is a population called Ctesifón, a large population. There they tend to have their winter residence the kings of labor, not disturbing the Seleucidas, so that they would not be oppressed by having the people and army spied among them. Thus, due to the birth power, Ctesphoon is rather a city; its size is such that it hosts a large number of people and the same births have equipped it with buildings. They have also equipped it with goods to sell and with the arts that please the labors; so the kings deliveries have the habit of spending here the winter for the salubrity of their air, but the summer in Ecbatana and in Hircania for the predominance of their old name.16, 16
During this century the construction of the Nahrawan Canal began.
Due to its importance, the city was a prominent military objective for the Roman Empire in its eastern wars. In such a way that the city was subdued by the Romans or their successor state, the Byzantine Empire, up to five times in its history.
The emperor Trajan conquered the city in the year 116; After a year of occupation, Hadrian's successor had no choice but to return it in 117 as part of a perpetual peace treaty with the Parthians.
The Roman general Avidius Cassius recaptured the city in 164 during the Roman-Parthian War of 161-166, but had to give it up when peace was made. In 197 the Roman emperor Septimius Severus sacked the city and moved thousands of its inhabitants to be sold as slaves.
At the end of the III century, after the Sassanid Empire, or Second Persian Empire, overthrew the Parthians, the The city was once again at war with the Romans. In 295, Galerius lost a battle against the Persians near the city. Humiliated, he returned a year later and won a great victory, which ended with the fifth and final capture of the city by the Roman army, although he returned it to Narses in exchange for Armenia. About 325 and again in 410 the city, or the Greek colony directly opposite, hosted a council of the Assyrian Church of the East.
The Roman emperor Julian the Apostate died before the city walls in 363 during the war against Shapur II. Finally, the Byzantine emperor Heraclius besieged the city, capital of the Sassanid Empire, in 627, liberating it once the Persians accepted his peace terms.
Madain
The Muslims conquered Ctesiphon in a relatively brief siege in 637 under the military command of Sa'ad ibn Abi Waqqas, calling it "the old city" (al-Madina al-Atika) and other nearby settlements., they formed Madain (al-Madain, The Cities, in Arabic: المدائن) under the caliphates of the Umayyads and Abbasids. During the last years it was the residence of the Jewish exilarch and the Nestorian Catholic.
The historian Abu'l-Hasan al-Mada'ini (753 – after 830) spent part of his life in the city, from whose Arabic name (Al-Madain) his own name comes.
Although the general population was not mistreated, the ancient city of Ctesiphon suffered rapid decline due to the loss of economic and political power, especially after the founding of Baghdad, the Abbasid capital in the 8th century, until it became a abandoned city. It is believed that the city of Isbanir from the eastern tale of The Thousand and One Nights is based on it.
Currently, Madain partly drifted to the new Iraqi city of Salman Pak, about twenty kilometers from ancient Ctesiphon and fifteen from Baghdad.
Between 1915 and 1916, the Battle of Ctesiphon, one of the largest operations of the First World War, was fought in the ruins of the city. There, the Ottoman Empire defeated British troops attempting to take Baghdad, driving them back some sixty kilometers before trapping the British forces and forcing them to surrender.
Population and religion
Under the Sassanid government, the population of Ctesiphon was very varied, from Arameans, Persians, Greeks or Assyrians. The two most used languages were Persian and Aramaic.
There was also a certain freedom of worship and Christianity, Judaism and Zoroastrianism coexisted. Also important was the group of Manichean believers who came to form the patriarchate of Babylon in Ctesifone. With the Muslims' capture of the city, many of these believers fled.
After the battle of Siffin, the population of Persian origin disappeared. In the IX century the surviving Manichaeans fled and moved their patriarchate to Samarkand.
Arch of Ctesiphon

The splendor of Ctesifonte's imperial palace complex was legendary. Includes the palace of the Persian king Cosroes I called the white palace (Shâhigân-CIA Sepid) and now destroyed almost completely and a huge arch (in Arabic, stakeholderاق كسرى Taq-i Kisra).
The throne room—presumably under or behind the arch—was more than thirty meters high. The large barrel vault covered an area of about twenty-five meters wide and fifty meters long, and is one of the largest brick vaults in the world.
The arch of Ctesiphon, or Taq Kisra, is today the only thing that remains of the city of Ctesiphon. The structure that has survived to this day is the main portico to the audience hall of the Sassanids, who maintained the same site that the Parthians had chosen for basically the same reason, its proximity to the Roman Empire, whose expansionist desire could be better contained. from here.
It is important for the use of brick, the arches, as can be seen on the façade, and the vaults, particularly the domes on squinches. The iwán also appears, or portico with a large arch open to a patio, which will later be adopted in Islamic art.
The arch is located in what is now the Iraqi city of Salman Pak (formerly Madain). The monument was being rebuilt in the 1980s after the northern wing of the building collapsed, but it was stopped after the Gulf War in 1991. After the fall of Saddam Hussein's government following the 2003 invasion of Iraq, during the following years it was They have proposed different plans for the restoration or improvement of the monument due to its tourist interest. The archaeological remains were on the verge of disappearing during 2015 and 2016 due to the threat of the Islamic State terrorist group, which led to a documentary by the director Iranian-Netherlandish Pejman Akbarzadeh (Taq Kasra: Wonder of Architecture).
The arc appeared in an aerial photograph presented to the contest brought by the writer Roald Dahl. It is mentioned, together with a copy of the image, in his autobiography "Boy".