Six of the Seven Wonders of the Ancient World left a physical footprint. The Hanging Gardens of Babylon left nothing, and generations of scholars concluded they were fiction. This episode treats the missing wonder as an archaeological cold case, starting with the traditional story that Nebuchadnezzar II built terraced gardens for his homesick Median wife, then asking why his exhaustive building records, the historian Herodotus, and modern excavations in Babylon are all silent.

The trail leads to Oxford scholar Stephanie Dalley’s theory that the gardens were real but stood 300 miles north in Nineveh, built by the Assyrian king Sennacherib. We look at his own inscriptions, his 50-mile network of canals and aqueducts with automatic sluice gates, his claim to have cast 30-ton bronze water screws, and a palace relief that appears to show the garden itself, along with how the historians traveling with Alexander the Great may have copied down the wrong city name.

• Why the Greek word behind hanging gardens really means overhanging, tiered terraces rather than hanging baskets
• The chain of classical writers, from Berossus to Diodorus, Strabo, and Philo, and what each claimed about the structure
• How the honorific title Gate of the Gods let Sennacherib rebrand Nineveh as a Babylon
• The Jerwan aqueduct’s two million limestone blocks, stone arches, and waterproof cement centuries before Rome
• The garden party relief, its imported cedar, cypress, and fig trees, and the severed enemy head hanging in the branches