Some of Dushanbe's major sights include the Tajikistan National Museum; the National Museum of Antiquities; the Ismaili Centre; Vahdat Palace; the Dushanbe Flagpole, which is the second tallest free-standing flagpole in the world, at a height of ; the Dushanbe Zoo; Rudaki Avenue, the main street of the capital; the Gurminj Museum of Musical Instruments; and the National Library, the largest in Central Asia, with 3.11 million copies of books.