Humans figured out around 500 BC that the Earth was a sphere and therefore must have a center line dividing the halves. In South America the ancient Quechua people named that equatorial line Inti (sun) Nan (path) centuries ago.
The modern-day marking of the line dividing the northern and southern hemispheres can be traced to the First Geodesic Mission. It was a French-led expedition, which arrived in 1736 in the Spanish territory of Quito. The expedition lasted nine years, was responsible for giving Ecuador its name, and succeeded in a fairly accurate measurement.
Although it turns out they probably should have just asked the natives, since modern GPS has proved that by simply observing the sun their line was more accurate than the French scientists’, who were off on the position of the equator, by about 240 meters. So, to get to the real Middle of the World, you will need to walk 240 m north to a place known as Intiñan Solar Museum.
Here you get to test a lot of fun stuff. Your balance is affected when you are on the equator and trying to walk a straight line with your eyes closed becomes impossible. Water, turns clockwise and counter-clockwise on either the north or south side and falls straight down when on the equator. Successfully balancing an egg is such a tremendous feat, that those who can do so receive a certificate. And last, but not least – don’t forget to get your passport stamped with 00° 00′ 00″ at the Middle of the World.