Today Is...The Great Fire Of London Starts

In 1666, Thomas Farriner, the Kings Baker who was working on the appropriately named Pudding Lane in London, decided he had enough for the day and would leave raking the coals out of his oven to the morning and went to bed.
Farriner, his family, and his servants were all awakened by the smoke but by then the ground floor of the bakery was on fire and he managed to escape from the flames by jumping from a window with his son clinging onto his back.
Soon he was stood watching the whole bakery burn to the ground and at this point the Lord Mayor of London turned up and mumbled that that the fire was so small that 'a woman might piss it out' and promptly went back home to sleep.
With the air smelling adorably of baking bread, the fire took advantage of the packed tightly together wooden houses together and spread to the neighbouring dwellings, then the rest of Pudding Lane, then the rest of the city and London continued to burn for four days and a full 80% of the city had been reduced to ash, destroying 13,200 houses, 84 churches and left 100,000 people homeless and six dead.
The silver lining to most of the cities wooden buildings being burnt down was a significant redevelopment of the city using bricks and stone including St. Paul's Cathedral that was rebuilt after the disaster but more importantly the redevelopment killed many of London’s rats and fleas that was spreading the plague and burned down the insanitary houses which were a breeding ground for the disease.