Nearly all kinds of ancient mythology and religions were constructed from early civilizations trying to make sense of their surroundings. The idea of science was completely unknown to them; rather they explained natural phenomena as done by mythical deities. In Greek mythology this is how we come to certain instances like Apollo, the sun god, or Zeus, the god of the heavens and sky.
The horrid acts of Auschwitz concentration camp really need no introduction. It is nearly impossible to discuss this topic with someone who does not know at least a few points about it. The acts, if applied to any other context, may be restricted to the older populous, but even children grow up knowing about the genocide of World War II.
"don't even give it a thought !"
Ancient Greece has laid way for some of the most influential people, systems and stories of our civilization. It is hard to believe on one hand because technology-wise the Greeks were very primitive, yet on the other hand they were essentially on of the earliest roots of Western civilization.
World War II was by far one of the most significant wars of all time. Ripples of the splash this war made on history are still being felt today. Even more so than its predecessor, this was the most comprehensive global war. The focal point is the European battle front but there was just as much, if not more in Asia and even in Africa and the Americas.