From Wikipedia

The Hanging Gardens Of Babylon

The Hanging Gardens of Babylon, also known as the Hanging Gardens of Semiramis, near present-day Al Hillah, Babil in Iraq, are considered to be one of the original Seven Wonders of the Ancient World. They were built by the Chaldean king Nebuchadnezzar around 600 BC. He is reported to have constructed the gardens to please his homesick wife, Amytis of Media, who longed for the trees and fragrant plants of her homeland Persia. The gardens were destroyed by several earthquakes after the 2nd century BC.

The lush Hanging Gardens are extensively documented by Greek historians such as Strabo and Diodorus Siculus. Through the ages, the location may have been confused with gardens that existed at Nimrud, since tablets from there clearly show gardens. Writings on these tablets describe the possible use of something similar to an Archimedes screw as a process of raising the water to the required height. Nebuchadnezzar II also used massive slabs of stone, which was unheard of in Babylon, to prevent the water from eroding the ground.