We'll start with the most popular theories about the gardens. They were likely located by the Euphrates River in what is now modern-day Iraq. The gardens didn't actually hang: They draped over the sides of terraces on a brick structure. Some accounts of the gardens claim that they grew as high as 75 feet (22.86 meters) in the air and that people could walk beneath them. Accounts from the classical writer Diodorus Siculus describe that the brick walls were 22 feet (6.7 meters) thick and 400 feet (121 meters) wide. And Philo wrote that there were several strata of flora and many levels of irrigation.