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.

The Culture High is the riveting story that tears into the very fibre of modern day marijuana prohibition to reveal the truth behind the arguments and motives governing both those who support and those who oppose the existing pot laws. With budgets to fight the war reaching billions and arrests for simple possession skyrocketing to nearly a million annually, the debate over marijuana's legality has reached epic proportions. "The Culture High raises the stakes with some of today's biggest names, unprecedented access to footage previously unobtainable, and incredibly moving testimonials from both sides of the spectrum. Top celebrities, former undercover agents, university professors and a slew of unforgettable characters from all points of view come together for an amusing yet insightful portrait of cannabis prohibition and the grasp it has on society as a whole. "The Culture High" will strip search the oddity of human nature and dare to ask the question: What exactly is going on here?

'Deliver Us from Drought' - Over the past years, Texas has experienced the worst drought in its recorded history. 97% of the scientific community agrees that human activity has contributed to extreme weather patterns around the world. But many Texans--legislators, community leaders and citizens--don't attribute their drought to humans, and have taken few if any initiatives to limit the state's CO2 emissions, currently the highest in the country. "The Resource Curse" - As humanity's appetite for energy grows exponentially, the extraction industry scrambles to the most remote regions on Earth. In the undeveloped Melanesian country of Papua New Guinea, America's Exxon Mobil has staked its claim to a $19 billion liquid natural-gas project. While some see Exxon's mammoth presence as the catalyst that will usher the underdeveloped country into the 21st Century, others predict the initiative could plunge its people into civil war.

Playing with Nuclear Fire' - In March 2011, the Tohoku earthquake in Japan created a tsunami that killed some 16,000 people and crippled the Fukushima Daiichi nuclear power plant. In the aftermath, the government and TEPCO, the plant's operator, withheld information about the extent of the damage. Three years later, citizens and the international community are left wondering if Japan really does have the situation under control, as the government is insisting, or if the danger is far greater than anyone is willing to admit. 'No Man Left Behind' - It's estimated that over a quarter million vets from recent wars have sought treatment for PTSD. Despite these statistics, veterans often face an uphill battle to get treatment, receiving inadequate attention and, most dangerously, overprescribed narcotics and other pharmaceuticals. Ryan Duffy meets veterans struggling with mental illness and addiction.

'The Coldest War': With the polar ice caps shrinking due to global warming, new trade routes are being exposed, along with billions of dollars' worth of natural-resource reserves. The five nations bordering the Arctic are readying themselves to fight for it. The problem is that there's one non-NATO country that already considers itself rightful owner of the region: Russia. With Vladimir Putin's recent military annexation of Crimea, there's a definite possibility its aggressions will boil over, returning the international community to precarious Cold War footing. We will head north to witness NATO forces participating in the largest polar military exercise in history. 'Heroin Warfare': Since the U.S. occupation of Afghanistan, heroin production in the region has skyrocketed, making the country the number-one producer by a large margin. Though Iran, Afghanistan's neighbor, is an ultraconservative country, Afghan heroin flowing across the border has actually caused Iran to have the worst heroin use problem in the world. Suroosh Alvi gets a rare look inside Iran to meet the suffering heroin addicts, and see how the country is coping with the illegal drug trade.

As tuition rates spiral beyond reach and student loan debt passes $1 trillion (more than credit card debt), IVORY TOWER asks: Is college worth the cost? From the halls of Harvard, to public colleges in financial crisis, to Silicon Valley, filmmaker Andrew Rossi assembles an urgent portrait of a great American institution at the breaking point. Through interviews profiled at Arizona State, Cooper Union, and Sebastian Thrun's Udacity-among several others-IVORY TOWER reveals how colleges in the United States, long regarded as leaders in higher education, came to embrace a business model that often promotes expansion over quality learning. Along the way we also find unique programs, from Stanford to the free desert school Deep Springs to the historically black all women's college Spelman, where the potential for life-changing college experiences endure.