We are in the grip of an allergy epidemic. 50 years ago one in 30 were affected, but in Britain today it is closer to one in three. Why this should be is one of modern medicine's greatest puzzles. In search of answers, Horizon travels round the globe, from the remotest inhabited island to the polluted centres of California and the UK. We meet sufferers and the scientists who have dedicated their lives trying to answer the mystery of why we are becoming allergic to our world.

In this documentary we moved to Ancient Egypt to learn their vision of the world, life and death, gods and magic. For the ancient Egyptians, the Nile was the main connection between their lives and an infinite supply of provisions. But its waters hid an underworld of darkness and mystery for its first settlers. The Nile was one the spiritual paths that combined life and death, the real world and the underworld.

Professor Jim Al-Khalili continues his investigation of the atom by looking at radioactivity, the Atom Bomb and the Big Bang, and even why we are here and how we were made. He shows that, in the quest to understand the atom, the mystery of how the entire universe was created became revealed

Every cosmologist and astronomer agrees: our Universe is 13.7 billion years old. Using cutting-edge technology, scientists are now able to take a snapshot of the Universe a mere heartbeat after its birth. Armed with hypersensitive satellites, astronomers look back in time to the very moment of creation, when all the matter in the Universe exploded into existence. It is here that we uncover an unsolved mystery as old as time itself -- if the Universe was born, where did it come from? Meet the leading scientists who have now discovered what they believe to be the origin of our Universe, and a window into the time before time.

Deep in the Bolivian Andes at the height of 13,000ft stands Tiwanaku, the awe-inspiring ruins of a monolithic temple city. Built by a civilisation who dominated a vast swathe of South America, it was abandoned 1,000 years ago. For centuries it has been a mystery - how did a civilisation flourish at such an altitude and why did it vanish? Jago Cooper journeys through Bolivia's spectacular landscape to investigate the origins of Tiwanaku and finds evidence of an ancient people with amazing understanding of their environment, whose religion was based on collective effort and ritual beer drinking.

Of the Seven Wonders of the Ancient World, the Hanging Garden of Babylon is the most elusive of these constructions of classical antiquity. While traces have been found of the Great Pyramid of Gaza, the Temple of Artemis at Ephesus, the Statue of Zeus at Olympia, the Mausoleum of Halicarnassus, the Colossus of Rhodes and the Lighthouse of Alexandria, centuries of digging have turned up nothing about the lost gardens of Babylon – until now.
Why, in the nearly 3,000 years since the gardens were presumably built, has no archeological evidence ever been found to support their existence? Is the Hanging Garden of Babylon a myth or a mystery to be solved?
Travel with Dr. Stephanie Dalley of Oxford University’s Oriental Institute and author of The Mystery of the Hanging Garden of Babylon, to one of the most dangerous places on earth, as she sets out to answer these questions and prove not only that the gardens did exist, but also identify where they most likely were located, describe what they looked like and explain how they were constructed.