Ani has been documented as an Armenian fortress since the 5th century. In the 10th century it developed into an important city. King Ascot III Bagratuni (951-977) made Ani the capital of his Armenian kingdom in 961. When the city was given to the Byzantines in 1045, it was widely known as the "City of 1001 Churches" and had more than 100,000 inhabitants. The largest church was the Cathedral of Ani, built between 989 and 1001 by the architect Trdat for the Armenian patriarch who moved to Ani.

In 1064 Ani was conquered by the Seljuks, which brought it under Islamic rule. At the end of the 12th century the city fell to the Christian Kingdom of Georgia. The Georgians used the Armenian Zakarids as vassals in Ani, under which the city experienced a last short period of prosperity. A siege by the Mongols could be fought back in 1226.
In 1239, however, Ani fell into Mongolian hands and large parts of the population were killed. In 1319 the fate of the city was sealed by an earthquake, whereupon the population slowly but steadily decreased from the 14th century. After 1534 Ani was part of the Ottoman Empire and was on the territory of the Russian Empire between 1878 and 1917.
In 1892/93 and 1904-1917 the first extensive archaeological excavations took place in Ani under the direction of the Russian Orientalist Nikolai Jakowlewitsch Marr. In April 1918, about 6000 moving archaeological objects were brought from Ani to Yerevan to save them from the advancing Ottoman army.
With the surrender of the Ottoman Empire in October 1918, Ani fell under the control of the newly founded state of Armenia. After the Turkish-Armenian War of 1920, Ani arrived in Turkey.

Today Ani is a ghost town and is known above all for the preserved testimonies of Armenian architecture. The only "inhabitants" are Turkish border guards, isolated tourists and residents of the neighbouring Turkish village of Ocakli.
Threatened by "restoration work", cultural vandalism, earthquakes and more recently also by ground vibrations (triggered by explosions in a quarry on Armenian territory), the future of this cultural monument is in question.
More or less preserved are parts of the double wall, the cathedral (completed in 1001 or 1010), some churches and chapels, the citadel and a palace that fell victim to "reconstruction" at the end of the 20th century.

The Church of the Redeemer (today a hollow semicircle)

In the past, access to the city was partly only possible with permission, since the area was a military restricted area for a long time. Due to the location directly on the border to Armenia, photography was partially prohibited, and some parts of the area were not accessible to civilians. In the course of the tourist development, the largest parts of the city were made freely accessible. Only the citadel (Turkish: Iç Kale) and the immediate border strip are still a military restricted area and may not be entered. Several former monasteries around Ani and in the Armenian province of Shirak, including Chtsgonk, Marmaschen and Horomos, are stylistically attributed to the architectural "style of Ani" of the 11th century. From 2012 Ani was on the tentative list for inclusion as a UNESCO World Heritage Site.

In 2016, the city was declared a World Heritage Site.