"It's like the Black Hole of Calcutta" is a phrase regularly used to describe an overcrowded or stuffy room.
But where does it come from?
Well, it is actually based upon a real historic event.
In 1756, a large number of British prisoners were crowded into a tiny cell in Calcutta, India.
Measuring just 14 x 18 feet, they spent a night in this jail in tropical temperatures with no water.
Less than a third survived.
This is the story of that event, plus the events that led up to it and the aftermath.
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