13,000 miles long and built continuously over a period of more than 1,800 years, the Great Wall of China is the world’s largest military structure. It’s also stuck together with rice.
In 2010, Chinese scientists at Zhejiang University in Hangzhou discovered that the mortar used to stick the main body of the wall’s Ming Dynasty bricks together was made from a mixture of slaked lime (a standard ingredient of builders’ mortar) and amylopectin, an organic compound made from a sticky stew of over-boiled rice.
This polysaccharide compound, when mixed with the mortar, made for a strong and all but impenetrable cement that in some areas of the wall is still so solid that even notoriously destructive wall-climbing plants and weeds have been unable to cause any visible damage in more than six centuries.