"Assembled the Grand Central piece today. So big." Talk about an understatement.
The "Grand Central piece" referred to by conceptual artist Eric Daigh on Twitter is the billboard he created using more than 100,000 Post-it Notes.
The artwork is on display at Grand Central Terminal in New York.
3M, which owns Post-its, celebrated its 30th anniversary by teaming up with Daigh and non-profit artistic organisation Publicolor to create colourful art with a difference.
Students were invited to enter a competition run by 3M to create a billboard design explaining how they envisioned their life in 30 years' time.
The winning design by teenage friends Allison Hilgert and Ysanne Taylor was then enlarged by Daigh and broken into 55 panels to be recreated with sticky paper, the Wall Street Journal reported.
The billboard is the biggest in the world - measuring 12m by 13m and weighing 1678kg, according to reports.
It took more than 320 hours to create the giant billboard.
"This is my first Post-it piece, but it probably won't be my last," Daigh said.
Also on display at Grand Central is a portrait created by Daigh using thousands of push-pins.
Daigh is renowned for his award-winning push-pin portraits based on photos of his family and friends.
He uses 25,000 pins in only five colours - red, black, blue, white and yellow - to create the illusion of skin tone and hair.
Daigh loves watching people as they try to comprehend how he could make his art look so life-like.
"That's a wonderful thing to watch somebody not really be able to understand what they're standing in front of," he said.