AGAINST THE GRAIN
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 sti