The city is home to many educational institutions, leading to a large student population and the nickname of "education city". The city is in proximity to many ancient capitals of Bengal, notably 'Lakhnoiti' or 'Lokhnaboti' and 'Pundra'. Rajshahi is famous for trade in many exotic items, including pure silk, mangoes and lychees. Attractive silk products are cheaper in Rajshahi than anywhere else in the country, with the city often referred to as the 'silk city'. There are also a number ancient mosques, shrines and temples in and around Rajshahi. The city of Rajshahi was declared as the happiest city in the world by the World Happiness Survey in 2006.