Answer:
The most impressive aspect of the Hanging Gardens of Babylon is the engineering required to build a hanging garden, which was unheard of at the time. The gardens, which were built in 600 BCE, were kept alive for many centuries, despite the fact that Babylon received very little rain to naturally water plants. Additionally, many of the plants in the gardens could not be found in Mesopotamia, which required the Babylonians to import exotic plants from other parts of the world.