The world's largest postcard measured 42.69 m² (459.511 ft²) and weighed over 300 kg (661.386 lb). 6,367 out of 7,813 photos were selected for the final postcard.
World's Largest Postcard
The German city of Krefeld created it and made it to the Guinness World Records.
World's largest postcard!
The World’s Largest Postcard