apparently, the Pentagon was built on ground that was a former US Gov't funded hemp research farm:
http://www.tokeofthetown.com/2010/05/100-year-old_government_hemp_farm_diaries_to_be_re.php
http://www.tokeofthetown.com/2010/05/100-year-old_government_hemp_farm_diaries_to_be_re.php
Never-before seen journals found recently at a garage sale outside Buffalo, N.Y., chronicle the life of Lyster Dewey, who tended a United States government hemp farm in the 19th and 20th centuries.
Dewey, a botanist at the U.S. Department of Agriculture, wrote in detail about growing strains of hemp called Keijo, Chinamington and others on a tract of government land known as Arlington Farm, reports Manuel Roig-Franzia of the The Washington Post.
If the "Arlington" part of that name sounds familiar -- as in Arlington National Cemetery -- that's because the acreage used to grow the hemp was handed over to the War Department in the 1940s for construction of the world's largest office building: the Pentagon.
So in addition to the already-known intertwining of the noble hemp plant and U.S. history, now it is revealed that the very location of the Pentagon itself was once covered with verdant fields of cannabis.