The dome that crowns Florence's great cathedral of Santa Maria del Fiore, the Duomo, is a masterpiece of Renaissance ingenuity and an enduring source of mystery. Still the largest masonry dome on earth, it is taller than the Statue of Liberty and weighs as much as an average cruise ship. Historians and engineers have long debated how its architect, Filippo Brunelleschi, kept the dome perfectly aligned and symmetrical as the sides rose and converged toward the center." More than four million bricks could collapse at any moment -- and we still don't understand how Brunelleschi prevented it. To test the latest theories, a team of U.S. bricklayers will help build an experimental "mini-Duomo" using period tools and techniques.

Can new emission-free electric planes replace our polluting airliners and revolutionize personal transportation in our cities? The film takes a ride in some quiet, energy-efficient, prototypes that are vying for success as electric flight takes off.
The race is on to stop the climate emergency and we're seeing more and more people really paying attention to their carbon footprint. Aviation is a fast-growing offender, but is it too slow to respond. Could rapid progress in electric technology change the equation?

This edition explores the vast grasslands of the continent, hauntingly beautiful regions inhabited by strange creatures - giant anteaters, armadillos, maned wolves, capybara and jaguars.

After filming for three years, Planet Earth finally captures the shy Mongolian gazelle. Only a handful of people have witnessed its annual migration. Don't miss the bizarre-looking Tibetan fox, captured on film for the first time. Over six weeks the team follow a pride of 30 lions as they attempt to hunt elephants. Using the latest night vision equipment, the crew film the chaotic battles that ensue at close quarters.

This episode includes footage of wildlife inhabiting underwater kelp forests, thousands of giant cuttlefish spawning along a restricted area of rocky reef off the south coast of Australia. Males outnumber females 11 to one, which leads to fierce competition. Larger males use brute force to drive off competition, while their smaller rivals use deception by mimicking the appearance of females. The programme also features tiger sharks hunting for green turtles in fields of seagrass and spider crabs trying to avoid predators while they shed their shells.

Timothy Treadwell's death was as sensational as his life: Having presumed he could live safely among the grizzly bears of the Alaskan wilderness, the outdoorsman and author (Among Grizzlies)--along with his partner, Amie Huguenard--was eventually killed and devoured by one of the very animals to whom he had devoted years of study.
In telling this story, Werner Herzog relies considerably on Treadwell's own video footage, shot during his time in the wild. The famed German director takes Treadwell's story into unexpected emotional frontiers and startling landscapes of the mind. Treadwell is an intriguing, infuriating, perhaps even tragic figure. But Herzog himself is equally compelling, and this brilliant film is just one reason why.