St. Gregory Illuminator’s church or the cathedral of Zvartnots and the residence of catholicos nearby were built by catholicos Nerses III the Builder in 641-661.
Khor Virap monastery is situated in Ararat valley, on the bank of Arax river, where Gregory Illuminator was imprisoned by king Tiridat III for 13 years.
On the territory of modern Martuni city there are ruins of a fortress, which was built by Urartian king Rusa I and was called “the city of Khaldi” – the god of the sky.
In the 9th century under the guidance of the future catholicos Mashtots - the leader of the Armenian church, sponsored by queen Mariam Bagratuni a monastery was built on the island of Sevan lake.