A modern day scourge to the church and subject of the not-so-great movie Kingdom of Heaven starring Liam Neeson and Orlando Bloom , they were launched by Pope Urban II in 1095.

In 1439 this dude invented this thing…and it changed the world (and your educational opportunities) forever.

Weakened as the inadvertent destination of the 4th Crusade, this Eastern capitol city and chief seat of the Byzantine Empire finally fell to invading Muslim Ottoman Turks in 1453.

Between 1347 and 1351, it killed 25 million people, single handedly.

"As soon as a coin in the coffer rings, a soul from purgatory springs” is an example of this.