Who built Stonehenge and why? Discover how the last decade of groundbreaking archaeological digs has revealed major new clues to Britain's enigmatic 5,000-year-old site and the people who constructed it.

Who built Stonehenge and why? Discover how the last decade of groundbreaking archaeological digs has revealed major new clues to Britain's enigmatic 5,000-year-old site and the people who constructed it.

Who built Stonehenge and why? Discover how the last decade of groundbreaking archaeological digs has revealed major new clues to Britain's enigmatic 5,000-year-old site and the people who constructed it.

More than two thousand years ago, the thriving city of Petra rose up in the bone-dry desert of what is now Jordan. An oasis of culture and abundance, the city was built by wealthy merchants whose camel caravans transported incense and spices across hundreds of miles from the Arabian Gulf. They carved spectacular temple-tombs into its soaring cliffs, raised a monumental Great Temple at its heart, and devised an ingenious system that channeled water to vineyards, bathhouses, fountains, and pools. But following a catastrophic earthquake and a slump in its desert trade routes, Petra's unique culture faded and was lost to most of the world for nearly a thousand years. Now, in a daring experiment, an archaeologist and sculptors team up to carve an iconic temple-tomb to find out how the ancient people of Petra built their city of stone. And beyond Petra's city of the dead, scientists using remote sensors and hydraulic flumes discover a city of the living-complete with a water system that not only supplied 30,000 people with enough to drink, but also filled bathhouses, fountains, and pools with such abundance that some scholars believe this desert metropolis may have been the Las Vegas of the ancient world. The race is on to discover how these nomads created this oasis of culture in one of the harshest climates on earth, and ultimately, why Petra disappeared.

More than two thousand years ago, the thriving city of Petra rose up in the bone-dry desert of what is now Jordan. An oasis of culture and abundance, the city was built by wealthy merchants whose camel caravans transported incense and spices across hundreds of miles from the Arabian Gulf. They carved spectacular temple-tombs into its soaring cliffs, raised a monumental Great Temple at its heart, and devised an ingenious system that channeled water to vineyards, bathhouses, fountains, and pools. But following a catastrophic earthquake and a slump in its desert trade routes, Petra's unique culture faded and was lost to most of the world for nearly a thousand years. Now, in a daring experiment, an archaeologist and sculptors team up to carve an iconic temple-tomb to find out how the ancient people of Petra built their city of stone. And beyond Petra's city of the dead, scientists using remote sensors and hydraulic flumes discover a city of the living-complete with a water system that not only supplied 30,000 people with enough to drink, but also filled bathhouses, fountains, and pools with such abundance that some scholars believe this desert metropolis may have been the Las Vegas of the ancient world. The race is on to discover how these nomads created this oasis of culture in one of the harshest climates on earth, and ultimately, why Petra disappeared.

Stunning new archaeological evidence provides clues about the Egyptians who built the Great Pyramid of Giza -- and how they did it. Join researchers as they delve into the logbook of a work crew and discover how the massive project transformed Egypt.

Istanbul's magnificent Hagia Sophia has survived on one of the world's most active seismic faults, which has inflicted a dozen devastating earthquakes since Hagia Sophia was built in 537 AD. As Istanbul braces for the next big quake, a team of architects and engineers is investigating Hagia Sophia's seismic secrets. NOVA follows the team's discoveries as they examine the building's unique structure and other ingenious design strategies that have insured the dome's survival. The engineers build a massive eight-ton model of the building's core structure, place it on a motorized shake table and hit it with a series of simulated quakes.

Istanbul's magnificent Hagia Sophia has survived on one of the world's most active seismic faults, which has inflicted a dozen devastating earthquakes since Hagia Sophia was built in 537 AD. As Istanbul braces for the next big quake, a team of architects and engineers is investigating Hagia Sophia's seismic secrets. NOVA follows the team's discoveries as they examine the building's unique structure and other ingenious design strategies that have insured the dome's survival. The engineers build a massive eight-ton model of the building's core structure, place it on a motorized shake table and hit it with a series of simulated quakes.

Stunning new archaeological evidence provides clues about the Egyptians who built the Great Pyramid of Giza -- and how they did it. Join researchers as they delve into the logbook of a work crew and discover how the massive project transformed Egypt.

Stunning new archaeological evidence provides clues about the Egyptians who built the Great Pyramid of Giza -- and how they did it. Join researchers as they delve into the logbook of a work crew and discover how the massive project transformed Egypt.

Wielding chainsaws to extract fossils frozen into the permafrost and flying drones to map thousands of footprints, intrepid paleontologists discover that dinosaurs thrived in the unlikeliest of places -- the cold and dark of the Arctic Circle.

Journey to the top of the world with scientists as they embark on the most ambitious Arctic research expedition of all time. The Arctic - a vast frozen ocean, shrouded in darkness for half the year - is warming at twice the rate as the rest of the globe. Since the northern ice cap acts as a cooling system for the entire planet, what happens in the Arctic doesn't stay in the Arctic. As the ice cap melts, the world warms faster, disrupting weather patterns, diverting ocean currents, and endangering biodiversity. Yet because the Arctic is so inaccessible and inhospitable, establishing exactly what's going on and forecasting its future have proven elusive. Now, Arctic Drift takes viewers on a groundbreaking expedition that will bring vital new clarity to scientists' predictions of global change. Experts from twenty different nations join the voyage of the 12, 000-ton Polarstern icebreaker as it's gripped by the polar ice and drifts for an entire year. From this unique research station, they can make previously impossible long-term observations and experiments. But long hours in this harsh environment bring their own challenges, including hungry polar bears, perilous sea ice cracks, and equipment failure. With breathtaking cinematography, heart-wrenching personal stories, and high stakes science, Arctic Drift follows the scientists in their risky race against time to understand the Arctic before it changes our world forever.

Journey to the top of the world with scientists as they embark on the most ambitious Arctic research expedition of all time. The Arctic - a vast frozen ocean, shrouded in darkness for half the year - is warming at twice the rate as the rest of the globe. Since the northern ice cap acts as a cooling system for the entire planet, what happens in the Arctic doesn't stay in the Arctic. As the ice cap melts, the world warms faster, disrupting weather patterns, diverting ocean currents, and endangering biodiversity. Yet because the Arctic is so inaccessible and inhospitable, establishing exactly what's going on and forecasting its future have proven elusive. Now, Arctic Drift takes viewers on a groundbreaking expedition that will bring vital new clarity to scientists' predictions of global change. Experts from twenty different nations join the voyage of the 12, 000-ton Polarstern icebreaker as it's gripped by the polar ice and drifts for an entire year. From this unique research station, they can make previously impossible long-term observations and experiments. But long hours in this harsh environment bring their own challenges, including hungry polar bears, perilous sea ice cracks, and equipment failure. With breathtaking cinematography, heart-wrenching personal stories, and high stakes science, Arctic Drift follows the scientists in their risky race against time to understand the Arctic before it changes our world forever.

Over the past few decades, the number of skyscrapers worldwide has climbed dramatically. And as developers look to maximize limited urban space, and nations vie for prestige, these shimmering towers are being built higher and higher. In China alone, dozens of buildings rise to over 1,000 feet, with a few approaching 2,000 feet. But for all their impressive engineering, are these buildings safe? And are building regulations keeping up with the soaring heights of new structures? In San Francisco, skyscrapers can be built on unstable, sinking ground. And internal sprinkler systems are the only hope for extinguishing fires that burn beyond the reach of firefighters' ladders. Now, NOVA explores the science behind the risks of sky-high buildings, from the structural limits of building materials to the threats presented by wind, fire, and earthquakes. Experts show how the science of evacuation has shaped buildings in recent years, and what we have-and haven't-learned from past tragedies.

Soaring skyscrapers are potent symbols of prestige, and architects are vying to build them ever higher. But can they find new ways to defend them against fires, wind, and earthquakes, as well as making them livable, interactive, and eco-friendly?

Explore the dramatic story of NASA's James Webb Space Telescope-the most ambitious observatory ever launched-through a series of high-stakes milestones, from its conception to completion.

Explore the dramatic story of NASA's James Webb Space Telescope-the most ambitious observatory ever launched-through a series of high-stakes milestones, from its conception to completion.

Murdered more than 5,000 years ago, Otzi the Iceman is the oldest human mummy on Earth. Now, newly discovered evidence sheds light not only on this mysterious ancient man, but on the dawn of civilization in Europe.

Murdered more than 5,000 years ago, Otzi the Iceman is Europe's oldest known natural mummy. Now, new revelations about Otzi's life and legacy come to light, including surprising secrets hidden in his genetic code.

A spectacular fossil graveyard reveals a 43-million-year-old whale that had four legs and could walk. Follow scientists as they search for new clues to how mammals moved from land into the sea to become the largest animals on Earth.