As a centre of Armenian culture, Yerevan is the site of Yerevan State University (1919), the Armenian Academy of Sciences, a historical museum, an opera house, a music conservatory and several technical institutes. The Matenadaran archives hold a rich collection of valuable ancient Armenian, Greek, Assyrian, Hebrew, Roman and Persian manuscripts. Yerevan has several large public libraries, a number of museums and theaters, botanical gardens and zoos. It is also at the heart of an extensive rail network and is a major trading centre for agricultural products. In addition, industries in the city produce metals, machine tools, electrical equipment, chemicals, textiles and food products.