Some amazing things happened on this day in history
On 20 June, 1756, 146 prisoners were locked into a cell known now to history as the "Black Hole of Calcutta." The Nawab of Bengal was the culprit, and according to legend, only 21 were alive in the morning.
In 1789, on this day, French assemblymen representing the common people shut themselves into a tennis court, and vowed to stay there until a constitution was drawn up. This was the start of the French Revolution.
In 1837, in another hugely historic moment, Princess Victoria was woken up with the news that her uncle, William IV, had died, having survived until her 18th birthday (which had happened on May 24), making her the heir to the British throne. Thus, the Victorian Age -- of railways, bridges, huge engineering achievements, and writers such as Charles Dickens -- was heralded.
On June 20, 1867, President Andrew Jackson purchased Alaska from Russia.
In 1893, a jury in New Bedford, Massachusetts, found Lizzie Borden innocent of the ax-murders of her father and stepmother. (Funnily enough, having seen the play and read all the stories, I thought she was convicted!)
And in 1963 the "hotline" between Russia and the United States was established.