The National Post Office, located in the north wing of a large building on the Dremton Lam (Drentoen Lam), is where the famous Bhutan's Philatelic Bureau sells stamps and souvenir sheets of Bhutan stamps. In view of their colourful presentation and limited issue, stamp collectors all over the world know that Bhutan is the first country to diversify and export quality stamps; particularly, 3D stamps are collectors items. Old stamps are now sold for profit. An agency in New York sells to the collectors and it is also locally printed by the Government of Bhutan.