The Gordian Knot was the Mount Everest of knot tying: a strap twisted and turned into such a tangle that it was impossible to see where it began and ended.
It was used to tether a legendary chariot belonging to an ancient king of the city of Gordium (in modern-day Turkey) to a pole outside the palace and destined to be untied only by a great ruler.
In fact, an oracle said that anyone who loosened the knot would rule all of Asia. That made too tempting a challenge for the uber-confident empire builder, Alexander the Great.
After conquering the region in 333 BC, he was shown the chariot and, according to myth, successfully loosened the Gordian Knot. The details of how he managed the feat differ, though. The most-retold account is that Alexander didn’t waste time trying to untie it, but simply drew his sword and cut through it.