Sanahin Monastery is an Armenian monastery founded in the 10th century in Sanahin in the Lori Province of Armenia.

The name Sanahin literally translates from Armenian as 'this one is older than that one', presumably representing a claim to being an older monastery than the neighbouring Haghpat Monastery, together with which it forms a UNESCO World Heritage Site. The two villages and their monasteries are similar in many ways, and lie in plain view of each other on a dissected plateau formation, separated by a deep crack formed by a small river flowing into the Debed river.

As with Haghpat, Sanahin is frequented by an increasing number of tourists, due to its recent inclusion on the itineraries of a great number of Armenian tour agencies, the beauty of its monastery complex matching that of Haghpat's. The complex belongs to the Armenian Apostolic Church with numerous khachkars (stones with elaborate engravings representing a cross) and bishop gravesites scattered throughout it.

The architectural complex of Sanahin monastery was formed during about three centuries. Each new building was built taking into account the operational role of the previous ones, the space and stylistic features. The complex includes the Church of St. Astvatsatsin and Surb Amenaprkich churches with their vestibules, the seminary, St. Grigor chapel, bookstore, bell tower, St. Hakob church, St. Harutyun chapel, the family tombs of the Kyurikyans, Zakaryans (Zakarid), Arghutyan-Yerkaynabazuk.

The main building material of the structures is local light gray polished basalt, which was used for roofing. The architectural forms and decoration are generally simple, monumental, with a restrained emphasis on cornices, doors, and window frames on flat wall surfaces. The artistic expression of the interior spaces was created by the combination of roofs, districts, vaulted arches, domes, with the simple, logical and symmetrical structure of the pillars bearing them.