More can always be said, but meanwhile take a look at this answer from /u/mythoplokos

https://www.reddit.com/r/AskHistorians/comments/5vw3ai/did_the_hanging_gardens_of_babylon_actually_exist/

Edit: One of the images (The Nineveh relief) linked in the answer above seems to have been lost to link rot, you can look at it here:

https://blog.britishmuseum.org/wp-content/uploads/2018/09/GardensFace1960.gif