These baseplates were released between 1985-1987 and used in the LEGO Classic Town Airport sets, specifically set number 6392 known as "Airport".
Genuine LEGO Green Baseplate Classic Building Range 32 x 32 Stud City
Vintage Lego 4478px2 Green Baseplate, Road 32 x 32 with Driveway with Light Gray
LEGO Classic Large Creative Brick Storage Box Set, Building Toys for 4 Plus Year Old Boys & Girls, Creative Construction Kit with Windows, Doors, Wheels and a Green Baseplate, Gift for Kids 10698
LEGO 11023 Classic Green Baseplate, Square 32x32 Stud Building Grass Base, Bu...
LEGO 11023 Classic Green Baseplate, Square 32x32 Stud Building Grass Base,...
