The final leg takes him from the Khyber Pass through Pakistan to the Punjab, where Alexander's army mutinied and he was forced to return across the Makran Desert to Babylon, where he died at only 32 years of age.

We’re going back to the moon. Plans are being made, hardware is being designed, built, and tested to return humans to the moon and beyond in a new era of American space exploration. This episode explores how we did it in the past, and how and why we will do it again. The moon is critical to future explorations: it will be where we learn to build sustainable colonies on other worlds.

Journalist and Youtuber Benjamin Cook hosts everyday people discussing a variety of attitudes towards sex. Tofu offers a 'honest, non-judgemental and entertaining view of sex and sexuality'

Embedding over the course of his seminar 'Date with Destiny', Joe Berlinger turns an unflinching eye on Tony Robbins powerful and uncompromising approach to achieving success, ensuring the attendees leave with new perspective on the forces, thoughts and feelings that motivate their behavior and help them better take control of their lives. The films pulls back the curtain on Tony Robbins, a man that traverses the globe and consults over 200,000 people annually, including world leaders, pundits and celebrities. An emotional tour de force that unveils the inner-workings of this mega event, the zealous participants and the man himself.

From the detection of gravitational waves generated in space over a billion years ago, to discoveries in genetics here on Earth, we've collected the most compelling science breakthroughs and advances of 2016. Thanks to magnificent, hard-working scientists and researchers around the world, science keeps marching ever forward. And this year saw some discoveries that are absolutely brimming with the promise of greater discoveries, breakthroughs and quality of life in the future.

Take a look back at many of the most fascinating science stories of 2017, a year full of stunning advancements in individual fields of study, from astronomy to biology, geology to history – when we piece these discoveries together we see the year in a new light.