From Cinderella to The Bachelor and The Bachelorette reality TV shows, and from lavish destination weddings to the marriage equality movement, getting married has taken center stage in the 21st century. What purpose has the institution served across the centuries? How do proposals, ceremonies, and expectations of marriage differ across cultures? What can couples do to ensure a strong marriage, and what happens if they can't make it work? See how answers to these questions have changed across the centuries, and hear what long-term married couples have to say about the secret to their success.