There is a 600 year old 240 paged book called the Voynich Manuscript, that’s written language is still completely unknown today.
15
There are pictures of Knights fighting Snails in old Medieval manuscripts - and nobody knows why.
23
In 1518, a "dancing plague" struck Strasbourg, Alsace, whereby hundreds of people danced fervently in the streets over the period of a month. Some suffered heart attacks or strokes, and many others died from sheer exhaustion. It remains unexplained.
19
India invented the Number System. Zero was invented by Aryabhatta.
59
Leonardo da Vinci was dyslexic, and he often wrote backwards.
77
In 2011, a couple bought a box of textbooks for $10. Inside, they found a 25-cent bill signed by the president of the Republic of Texas, Sam Houston, and subsequently sold it for $63,250.
13
During WW2, captured German officers were sent to Britain as POWs and lived in luxury in Trent Park. This was done to make them feel relaxed. However, they were being listened to by 100 ‘listeners’. They revealed secrets about the holocaust, events in Berlin, Hitler's madness and V2 rocket bases.
17

