Inside Britain's Most Mysterious Cave [5:42]

Hertfordshire: A sealed cave rediscovered by accident - carved with Christian symbols, pagan marks, and apotropaic signs. This hidden chamber has been linked to Knights Templar theories, Holy Grail legends, Reformation-era secret worship, and the life of a medieval wayside hermit. Inside the chamber are carvings of knights, crucifixion scenes, protective marks, and a figure many identify as the medieval king Richard I - all cut directly into the chalk. Some theories point to Templar connections and the Holy Grail, others to hidden worship during the Reformation or a solitary hermit carving his devotion into the walls. What's certain is...