As importantly, while the Nazis killed many non-Jews, they did not kill (in the camps, anyway) a notable percentage of any group other than Jews--no other population was almost wiped out, or even came close.
However, I must respond to amm14's comment. It is inaccurate to say that Jews were the only population that was almost wiped out. Not at all to reduce the devastation experienced by the Jewish people, cultures, and communities, but the Romani genocide, or the Porajmos, was also devastating for the Romani people, cultures, and communities. Some historians estimate up to 75% Romani in Europe (between 1.5-2 million people) were murdered.
The eugenic, racist maniacs who orchestrated the Holocaust are evil, and all the human suffering they caused is a historic tragedy. But the Jews, and also the Romani, suffered an all-out assault on their very existence.
but Wikipedia confirms that there are some who doubt the gardens ever existed, or that they existed in Babylon, or that they were accurately described in Greek tests. There are others who believe they existed as described and were simply destroyed. I'm not sure if I would call them apocryphal since there seems to be no consensus.
The rest of them I know from history books.