The Roman Republic is one of the most breathtaking civilizations in world history. Between roughly 500 BCE to the turn of the millennium, a modest city-state developed an innovative system of government and expanded into far-flung territories across Europe, Northern Africa, and the Middle East. This powerful civilization inspired America's founding fathers, gifted us a blueprint for amazing engineering innovations, left a vital trove of myths, and has inspired the human imagination for 2,000 years.

Military history often highlights successes and suggests a sense of inevitability about victory, but there is so much that can be gleaned from considering failures. Study these crucibles of history to gain a better understanding of why a civilization took - or didn't take - a particular path.

England: From the Fall of Rome to the Norman Conquest takes you through the mists of time to the rugged landscape of the British Isles. Over the course of 24 sweeping lectures, Professor Jennifer Paxton of The Catholic University of America surveys the forging of a great nation from a series of warring kingdoms and migrating peoples. From Germanic tribes to Viking invasions to Irish missionaries, she brings to life an underexamined time and place.

In a field known for startling ideas, the Many-Worlds Interpretation (MWI) of quantum mechanics may take the prize. It holds that parallel to our own world are a large number of other universes, almost identical to ours but with small variations. Copies of each of us inhabit a myriad of these worlds. But they are not us exactly; they share our past history, but they are different people who have unique futures. Although these realms are invisible and can’t communicate with each other, prominent physicists are convinced they must exist.

Look beyond the abstract dates and figures, kings and queens, and battles and wars that make up so many historical accounts. Over the course of 48 richly detailed lectures, Professor Garland covers the breadth and depth of human history from the perspective of the so-called ordinary people, from its earliest beginnings through the Middle Ages.

Grasp the important ideas that have served as the backbone of philosophy across the ages with this extraordinary 60-lecture series. This is your opportunity to explore the enormous range of philosophical perspectives and ponder the most important and enduring of human questions-without spending your life poring over dense philosophical texts.

With this exciting and historically rich six-lecture course, experience for yourself the drama of this dynamic year in medieval history, centered on the landmark Norman Conquest. Taking you from the shores of Scandinavia and France to the battlefields of the English countryside, these lectures will plunge you into a world of fierce Viking warriors, powerful noble families, politically charged marriages, tense succession crises, epic military invasions, and much more.

Alexander was born into the royal family of Macedonia, the kingdom that would soon rule over Greece. Tutored as a boy by Aristotle, Alexander had an inquisitive mind that would serve him well when he faced formidable obstacles during his military campaigns. Shortly after taking command of the army, he launched an invasion of the Persian Empire, and continued his conquests as far south as the deserts of Egypt and as far east as the mountains of present-day Pakistan and the plains of India.

In The Pagan World: Ancient Religions Before Christianity, you will meet the fascinating, ancient polytheistic peoples of the Mediterranean and beyond, their many gods and goddesses, and their public and private worship practices, as you come to appreciate the foundational role religion played in their lives. Professor Hans-Friedrich Mueller, of Union College in Schenectady, New York, makes this ancient world come alive in 24 lectures with captivating stories of intrigue, artifacts, illustrations, and detailed descriptions from primary sources of intriguing personalities.

Having done field work in New Guinea for more than 30 years, Jared Diamond presents the geographical and ecological factors that have shaped the modern world. From the viewpoint of an evolutionary biologist, he highlights the broadest movements both literal and conceptual on every continent since the Ice Age, and examines societal advances such as writing, religion, government, and technology.

Whether taken as a book of faith or a cultural artifact, the New Testament is among the most significant writings the world has ever known, its web of meaning relied upon by virtually every major writer in the last 2,000 years. Yet the New Testament is not only one of Western civilization’s most believed books, but also one of its most widely disputed, often maligned, and least clearly understood, with a vast number of people unaware of how it was written and transmitted.

Between 1861 and 1865, the clash of the greatest armies the Western hemisphere had ever seen turned small towns, little-known streams, and obscure meadows in the American countryside into names we will always remember. In those great battles, those streams ran red with blood-and the United States was truly born.

The Mongol army led by Genghis Khan subjugated more lands and people in 25 years than the Romans did in 400. In nearly every country the Mongols conquered, they brought an unprecedented rise in cultural communication, expanded trade, and a blossoming of civilization.

"It doesn't take an Einstein to understand modern physics," says Professor Wolfson at the outset of these 24 lectures on what may be the most important subjects in the universe: relativity and quantum physics. Both have reputations for complexity. But the basic ideas behind them are, in fact, simple and comprehensible by anyone. These dynamic and illuminating lectures begin with a brief overview of theories of physical reality starting with Aristotle and culminating in Newtonian or "classical" physics.