The seven-day week has shaped the lives of billions of people around the world, but where did it come from? While many assume it was prescribed in the Bible, the story in Genesis is actually describing a practice that already existed.

To find the origin of the seven-day week, one has to go back to ancient Babylon. The Babylonians recognized the 7th, 14th, 21st, and 28th days of the month as religiously significant and built a seven-roomed tower in celebration of a seven-day festival.

While the exact reason for the choice of a seven-day week is unknown, there are three theories that are pretty well accepted among historians. The first theory is based on the Babylonians' interest in the number seven, which was significant in some of the most prominent constellations like the Big Dipper and the Pleiades. The second theory is based on the fact that the Babylonians named the days after the planets, which were also the names of some of their gods. The last theory is based on the belief that the number seven had a cosmological importance.