Story : They are the largest baths of all time. They are located in Rome and have resisted looting and destruction over the centuries. They are the Baths of Emperor Diocletian. Alberto Angela went to visit them to discover their history, their architectural structure and their artistic treasures. For the usual appointment with the documentary, the second episode of the BBC series "Blue Planet" dedicated to the Ocean will be proposed. This evening we will talk about the so-called "coral seas", the richest and most colorful communities of all the seas in the world. Spectacular images of coral reefs, true underwater paradises. Guest in the studio is Dr. Donata Lodi of UNICEF with whom Piero Angela will address the sad topic of infibulation. A mutilation, a painful cut, an indelible mark. There are at least 40 countries in which the practice of genital mutilation on small victims is widespread.