Kolkata GPO was designed in 1864 by Walter B. Grenville. The site of this building was the same place were the Fort Williams once existed. The construction work of the post office was completed in 1868. The building has a high domed roof with a clock (purchased from London at a cost of Rs. 7000) This two storied building was constructed at a cost of Rs. 6.5 lakhs. A postal museum and philatelic library was opened on November 2nd 1979.The museum displays a wide collection of artefacts and stamps. The south-western end of the building houses Philatelic Bureau.