The Great Courses: The World of Byzantium by Kenneth W. Harl
This lecture series provides incredible detail into the world of Byzantium and its relationships to other civilizations over the millennium of its existence. This is a time period during the middle ages that I, and many I know, lack much knowledge.
The only complaint I have is that the information comes too fast. It really is designed as a lecture, where you can sit and take notes. Not having that opportunity, I suspect I will not retain much, but the lecture would be worth a second hearing.