It's this moment where now both sides realize that no quarter will be asked, and no quarter will be given. Surrender is no longer even an option. You're in this to the end. You either die or you triumph, and there is no other alternative. Amid a spiral of brutality and low morale, Mehmed makes Giustiniani an enticing offer. The grand vizier urges Mehmed to seek a truce with his rival.

Mehmed II sends his elite troops into the teeth of Emperor Constantine's defenses along the city's ancient stone walls. The defenders, led by Italian soldier-of-fortune Giovanni Giustiniani, repel every attack. Mehmed's men dig underground tunnels in an attempt to shatter city walls. The tides turn against the Ottomans when a naval blockade founders.

When Homo sapiens, which means 'wise ones,' discovered and controlled fire hundreds of thousands of years ago, everything changed. Fire allowed us to cook food and heat dwellings, and it served as a focal point for storytelling and sharing cultural identity among community members. We don't yet have established parameters for what it means to be 'distinctly human,' It would seem the only thing that separates us from other animals, Neil deGrasse Tyson ponders, is our neurotic need to feel 'special'. Against the backdrop of the Halls of Extinction, Tyson insists that there must be a clear distinction between ourselves and animals that justifies our eating them, wearing them and even bringing an end to their species.
From the birth of the devil in ancient Persia to a searing story of saintliness among macaque monkeys, this episode is an exploration of human potential for change. It concludes with the story of how one of history's greatest monsters was transformed into one of its shining lights.

Millions of tourists photograph the ancient monuments of Rome every year. But is there more to them than people guess? There's new evidence that these ruins were once machines, designed by Rome's emperors to connect their power with the sun. Did Roman emperors harness the power of the universe to awe and terrify the people of Rome? We uncover the last, great mysteries of the ancient world's greatest empire.

Astrology, the celestial movements of the Sun, Moon, and planets among the stars, governing our personality and destiny. For centuries, millions of people, from paupers to powerful world leaders, have relied on the ancient system for answers. This episode examines whether tracking astronomical phenomena can actually predict the future.

We are the generation of human beings that are going to know whether or not we're alone in the universe. This episode explores the search of exoplanets, from ancient Greek philosophers to the discoveries made possible with the Kepler Telescope. Unbelievable new worlds, planets made of diamond, planets of raining glass, worlds in collision, some plunging into stars, and others that just might harbor life.
Thanks to today's planet hunters, our views of the universe and of our place in it are undergoing one of the greatest revolutions in scientific history.