The disappearance and fate of the tomb of Alexander the Great in Alexandria is among the most momentous and tantalising of all the mysteries we have inherited from the ancient world. Generations of scholars and historians have succumbed to the allure of the quest.
Now archaeologist Pepi Papakosta is on a mission to find Alexander the Great's lost tomb. Excavating in a public garden in the center of Alexandria, Egypt, the city he founded 2,300 years ago, she has discovered a rare marble statue of Alexander, Greek treasures and secret tunnels. But Pepi's biggest find is an extraordinary discovery even she was not expecting.

Grasslands feed the world. Over thousands of years, we humans have learned to grow grains on the grasslands and domesticate the creatures that live there. Our success has propelled our population to almost seven billion people. But this episode reveals that, even today, life in the 'Garden of Eden' isn't always rosy. We walk with the Dorobo people of Kenya as they bravely attempt to scare off a pride of hungry lions from their freshly caught kill. We gallop across the Steppe with extraordinary Mongolian horsemen who were 'born in the saddle'. And in a perfect partnership with nature built up over generations Maasai children must literally talk to the birds! The honeyguide leads them to find sweet treats, but they'll have to repay the favour.

Southern Africa is a riot of life and colour because of two great ocean currents that sweep around the continent's Cape. To the east, the warm Agulhas current generates clouds that roll inland to the wettest place in southern Africa. To the west is the cold Benguela current, home to more great white sharks than anywhere else. Moisture laden fog rolls inland, supporting an incredible desert garden. Where the two currents meet, the clash of warm and cold water creates one of the world's most fabulous natural spectacles - South Africa's sardine run. This is the greatest gathering of predators on the planet, including Africa's largest, the Bryde's whale.

The world of invertebrates exists in a web of relationships with plants and other animals. Unique footage of the world's smallest insect (a fairy wasp only quarter of a millimetre long) shows it flying underwater to find the eggs of water beetles in which to lay its own brood. Some ants 'farm' the trees that give them shelter, creating areas known as 'Devil's gardens'. To make sure these grow without competition, they kill off other seedlings in the surrounding vegetation. The blister beetle's larvae huddle together on the end of a piece of grass and mimic a female bee. When a male bee tries to mate with the 'female', the larvae grab on to his belly. Confused, he flies away and searches for a real female. When he eventually finds her and mates with her, the beetle larvae hurriedly swap from his front on to her back, and hence get carried back to her nest where they eat her pollen supplies.

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.

As the early June sun begins to set over a calm river in Central Hungary, masses of ghostly shapes emerge from their larval cases to take to the air for the first time. They are mayflies and in a spectacular display, thousands of them demonstrate how the very first wings were used. From the stunning aerobatics of hoverflies in an English garden to the mass migration of purple crow butterflies in the valleys of Taiwan, this episode tells the tale of the first animals ever to take to the air. Unique footage reveals the lightning fast reactions of bluebottles and hoverflies, filmed with one of the world's fastest cameras, and Sir David Attenborough handles the world's largest (and perhaps most ferocious) insect - the Titan beetle.