Matenadaran is one the world’s richest repository of ancient manuscripts, where about 18,000 manuscripts and 300,000 documents are kept. The main objective of the museum is to preserve, restore and reproduce the manuscripts and to distribute and publish particularly historically significant manuscripts in languages other than Armenian. It holds one of the world’s richest depositories of medieval manuscripts and books of numerous subjects, including history, philosophy, medicine, literature, art history and cosmography in Armenian and many other languages.
In 1997 Matenadaran is registered among the UNESCO World memoirs. You are to pay 1,000 Dram (~$3) for the entrance and if you want to photograph, get ready to pay a little more. There are also guides to explain you the details.