Alberto Angela dedicates the first of the two episodes to the beauties of Rome. But this time we will talk about a "hidden" eternal city that centuries and centuries of construction have buried. Rome under Rome. The hidden secrets of the city. They will be told through little-known locations, never-discovered treasures, secret doors and unexplored dungeons. One for all, the Baths of Trajan in the park of Colle Oppio, where the largest Roman wall mosaic ever discovered was found: 300 square meters discovered, but a part is still buried and to be brought to light. The Basilica of Porta Maggiore, discovered by chance during work on the railway viaduct leading to Termini Station. In the Appio Latino neighborhood, under a manhole, is a hypogeum hidden with magnificent frescoes, where Christian and pagan symbols mix? This too was discovered by chance, while laying the foundations of a building. Alberto Angela will make us relive the activity that he carried out in these spaces.