Discover a land as exotic as it is extraordinary. Arabia offers an in-depth understanding of one of the most fascinating lifestyles and cultures. Cross the dunes with a caravan of camels, dive in the treasure-filled Red Sea, explore the ruins of the lost city of Petra, and relive the golden age of Islamic inventions. A precious land imprinted with myths and mysteries.

In the days of the Mayas, cenotes – deep, natural pits on the Yucatan peninsula - provided the only means of obtaining drinking water. But in the mythology of this advanced civilisation, these waterholes and caves were also the entrance to Xibalba – the underworld. All deceased were obliged to pass through Xibalba and wait there until they were called into heaven. It was a place in which one made sacrifices to the gods – objects of daily life, as well as bloody, human sacrifices. To this day, the relics of these acts are still in place preserved underwater for more than a thousand years. The entrance to the underworld begins at a dirty waterhole in the middle of the Mexican jungle overgrown and barely recognisable. But immediately after entry, a hall of breath-taking dimensions and beauty is revealed. As if they were sculptures, stalactites and stalagmites lend the underwater cave an almost sacred ambience. By now, one has succumbed to the fascination emanated by the world’s largest underwater cave system. We accompany four professional research divers to Yucatan – a team of specialists, able to squeeze their bodies through crevices and holes, barely larger than their bodies and who master dives that would push even the most experienced divers to their limits. With them, we penetrate worlds only a few people have ever ventured into. We encounter the remains of human victims, prehistoric fireplaces and primeval animal skeletons and undertake a dive, which takes us from the primeval forest to the open sea. We then enter Xibalba – the place of myths and the dead. In the days of the Mayas - a voyage of no return. Today, this is one of the greatest challenges one can face as a diver – the hidden world of the underwater caves of Yucatan – all filmed in 3D.

Birds of paradise are one of David Attenborough's lifelong passions. He was the first to film many of their beautiful and often bizarre displays, and over his lifetime he has tracked them all over the jungles of New Guinea. In this very personal film, he uncovers the remarkable story of how these 'birds from paradise' have captivated explorers, naturalists, artists, film-makers and even royalty. He explores the myths surrounding their discovery 500 years ago, the latest extraordinary behaviour captured on camera and reveals the scientific truth behind their beauty": the evolution of their spectacular appearance has in fact been driven by sex. And in a final contemporary twist to this story of obsession and royalty, he travels to the desert of Qatar, to a state-of-the-art facility which houses the largest breeding group of these birds in the world - a sheikh's very own private collection. There he has his closest ever encounter with a greater bird of paradise and its dramatic display, reliving the experience that captivated him in the forests of New Guinea more than 50 years ago.

Two thousand years ago one of history's most notorious individuals was born. Professor Mary Beard embarks on an investigative journey to explore the life and times of Gaius Julius Caesar Augustus Germanicus - better known to us as Caligula. Caligula has now become known as Rome's most capricious tyrant, and the stories told about him are some of the most extraordinary told about any Roman emperor. He was said to have made his horse a consul, proclaimed himself a living God, and indulged in scandalous orgies - even with his own three sisters - and that's before you mention building vast bridges across land and sea, prostituting senators' wives and killing half the Roman elite seemingly on a whim. All that in just four short years in power before a violent and speedy assassination in a back alley of his own palace at just 28-years-old." But how much of his story is true? Travelling across the Roman world - from Germany and Capri in the bay of Naples to the astonishing luxury of his life in imperial Rome - Mary attempts to peel away the myths. Some stories are difficult to get to the bottom of as they were written by hacks long after his death, but there is plenty of surviving evidence where the 'real' Caligula can be glimpsed. Such as in the extraordinary luxury of his private yachts outside Rome; in the designs he chose for his coins when he became Emperor; in an eye-witness account of Caligula's withering humour written in 41AD; the trial documents covering the mysterious death of his father when he was just seven-years-old; and even in a record of his imperial slaves - from the palace spy to his personal trainer. Piecing together the evidence, Mary puts Caligula back into the context of his times to reveal an astonishing story of murder, intrigue and dynastic family power. Above all, she explains why Caligula has ended up with such a seemingly unredeemable reputation. In the process, she reveals a more intriguing portrait of not just the monster, but the man.

The BBC's definitive television history of the rise and fall of the Nazis. The series explores how the Nazis came to power, how they ruled, how they treated their occupied territories and, above all, how a cultured nation could be responsible for such acts of inhumanity. How could a political party as fundamentally evil and overtly racist as the Nazis come to power? Acclaimed historian Laurence Rees exposes popular myths and encourages understanding of the real forces that led to one of the darkest chapters in modern history. Was it simply the hypnotic power of Hitler's rhetoric? Did the Gestapo really impose themselves by terror on an unwilling population?

The BBC's definitive television history of the rise and fall of the Nazis. The Nazis - A Warning From History exposes the popular myths surrounding the rise and fall of the Third Reich. The series explores how the Nazis came to power, how they ruled, how they treated their occupied territories and, above all, how a cultured nation could be responsible for such acts of inhumanity. How could a political party as fundamentally evil and overtly racist as the Nazis come to power? This remains one of the most enigmatic questions of the last century. Acclaimed historian Laurence Rees examines what led a cultured nation at the heart of Europe to commit the atrocities it did. In so doing, he exposes popular myths and encourages understanding of the real forces that led to one of the darkest chapters in modern history. Was it simply the hypnotic power of Hitler's rhetoric? Did the Gestapo really impose themselves by terror on an unwilling population? Through interviews with witnesses and perpetrators, along with archive film and records, this six-part series unveils a more chilling reality.