The ancient trade route between India and Tibet that passed through Kathmandu enabled a fusion of artistic and architectural traditions from other cultures to be amalgamated with local art and architecture. The monuments of Kathmandu City have been influenced over the centuries by Hindu and Buddhist religious practices. The architectural treasure of the Kathmandu valley has been categorized under the well-known seven groups of heritage monuments and buildings. In 2006 UNESCO declared these seven groups of monuments as a World Heritage Site (WHS). The seven monuments zones cover an area of 188.95 hectares (466.9 acres), with the buffer zone extending to 239.34 hectares (591.4 acres). The Seven Monument Zones (Mzs) inscribed originally in 1979 and with a minor modification in 2006 are Durbar squares of Hanuman Dhoka, Patan and Bhaktapur, Hindu temples of Pashupatinath and Changunarayan, the Buddhist stupas of Swayambhu and Boudhanath.