Slavery in the United States has left deep, unhealed wounds in American society. It was a dark period in American history that saw the emergence of a number of heroes. One of these was a small woman, about five feet tall, who was a former slave. Her name was Harriet Tubman, and she changed the world. After escaping from a life of slavery that left her with permanent scars including a lifelong disability, she dedicated herself to freeing other slaves and working tirelessly for equality for oppressed people.

The British Empire comprised a bewildering collection of colonies, dominions, protectorates, and mandated possessions that spanned the planet. This was the largest empire in world history, at its peak ruling over more than 400 million people and covering almost one-quarter of the total land mass of the Earth.

The creation of the Union of Soviet Socialist Republics (USSR) in 1922 was one of the defining events of the 20th century. This new federation, created to embody the ideals of communism and the notion of rule by the people, was intended to be different from any other nation in the world. This utopian vision inspired people around the world, and soon, communism became an international movement. However, the history of the Soviet Union did not develop in the way its originators envisaged.

The Spanish Empire was the first truly global empire and the first to be described as one on which “the sun never sets.” It rapidly grew to become one of the largest and most powerful empires in the history of the world and brought us goods such as potatoes, chocolate, and chewing gum.

World War I, or the Great War, was believed to be "the war to end all wars". Because of the incredible extent of destruction and the staggering number of wounded and dead, even those who lived through it could scarcely comprehend its horror. Beginning in 1914, alliances between powerful nations soon plunged the world into a global conflict. Fighting - including miserable trench warfare - broke out in practically every corner of Europe and spread around the world to Africa, Asia, and the Middle East.

Apartheid, a state-sponsored policy of discrimination and segregation, was introduced and brutally enforced in South Africa for more than 40 years. It led to thousands of deaths, mass arrests, torture of prisoners, and to the suspension of the most basic human rights for the majority of Black South Africans. How did this come to be, and how did a modern state come to enact and enforce a series of laws deliberately designed to ensure poverty and lack of opportunity for the majority of its population?

Rome is a city of myth and legend. The Eternal City, the city of the seven hills, the sacred city, the caput mundi, the center of the world, Roma, Rome, by any of her many names is a city built of history and blood, marble and water, war and conquest. From legendary beginnings, a city rose from the swamp surrounded by the seven hills and split by the Tiber River. Built and rebuilt, a sacred republic and a divine empire, blessed by a thousand gods and by One, the story of her rise and fall has been told and retold for a thousand years and is still relevant in today's world, as echoes of her ancient glory have shaped our culture, laws, lifestyle, and beliefs in subtle and pervasive ways.

Constantine the Great was one of the most pivotal figures in the history of the Roman Empire and the widespread expansion of the Christian religion. This is in no way an understatement; Constantine was not only one of the last truly powerful Roman emperors, but he also successfully reconstituted the whole empire according to his vision of Rome’s future. He played the most significant role in transforming the Empire from a Greco-Roman pagan dominion into a bulwark of the Christian faith, granting for the first time real temporal power for the early Christian church.

What do you think of when you consider the Middle Ages? Knights in armor and damsels in distress? Vikings plundering monasteries? Religious dissenters burning at the stake? The dead bodies piling up as war, famine, and plague devastated Europe? Think again. While all these are part of the tapestry of the medieval era, the threads of politics, personality and war, culture, religion, education and the arts are vastly more intricate and fascinating.

Violent confrontation between armed groups over the supply of illegal narcotics is something we commonly associate with criminal gangs in modern cities, but in the mid-19th century Great Britain went to war with Imperial China in order to continue to supply Chinese addicts with opium. The two wars that followed have become known as the Opium Wars, and they led to the utter defeat of China, the establishment of a British colony in Hong Kong, and the continuation of a narcotics trade that was worth millions of pounds each year to the British.

George Washington, the first president of the United States, is much more than a monument on Mount Rushmore. Who was Washington, the general, president, and husband? He was first and foremost a man of impeccable honor which, despite military adversity and political wrangling, never abandoned him. The Founding Fathers who squabbled and competed among themselves did agree on one thing: Only Washington could lead the country, first in the country’s military fight for freedom and then as the man charged with transforming 13 individual states into a united country.

Discover the remarkable history of the Inca Empire...In the space of less than one hundred years, the Inca people expanded from being a small kingdom in the highlands of Peru to becoming one of the largest and most powerful empires in the Americas. At the height of its power, the Inca Empire stretched for more than one thousand miles down the Andes Mountains and the west coast of South America. It incorporated more than two hundred distinct ethnic groups and somewhere around fourteen million people were ruled by a much smaller number of Incas.

During the bitter winter of 1692/93, a group of young Puritan women in the colonial town of Salem, Massachusetts, accused more than 200 of their neighbors and fellow townspeople of using witchcraft to injure and torment them. This was an incredibly serious allegation that led to sensational court proceedings and ended with the execution of 19 people.

Rosalind Franklin was what can only be called an overlooked genius. Although she was not fully credited for the feat at the time, her work led to major breakthroughs in our understanding of DNA. In fact, she took the first X-ray photo of DNA in all of its double helix glory. By the time her former colleagues were being showered with accolades for results they made at least partially based on her findings, Franklin would not be around to see it. Sadly, it’s believed that her use of X-ray equipment gave her terminal cancer, cutting her life short at age 37.

He was a husband, a father, a preacher - and the preeminent leader of a movement that continues to transform America and the world. Now, in a special program commissioned and authorized by his family, here is the life and times of Martin Luther King, Jr. Featuring King's I Have a Dream Speech.