Join Professor Darius Arya to explore the hidden secrets of the most fascinating cities of the ancient world. Tonight, See how 3D scanning can be used to reveal treasures of Athens, from the buildings on the Acropolis to the silver mines and quarries beyond the city. Then explore Egypt's ancient treasures, including the Great Pyramid of Giza and the first pyramid ever built, a hidden Roman fortress, and a well deep in the rock below the Arabic citadel of Saladin.

Two back-to-back episodes of Ancient Invisible Citiesair tonight at 9pm on WGBH 2.