I've been listening to Dan Carlin's Hardcore History Podcast for a long time now and i thought i would pass this gem along to you!
This guy puts out some awesome free content all devoted to history. Trying to be as unbiased as possible, he really paints a vivid picture of whatever subject he is covering. The average episode is 2 1/2 hrs long and some of his best pieces are series. If you have a long commute, or just want to chill and learn something new, I highly recommend this podcast (if you haven't discovered podcast's yet, prepare to have your mind blown by the sheer amount of free knowledge out there).
Some notable episodes/series:
- Wrath of the Khans (5 part series documenting the rise and fall of the Mongol Empire)
- Death Throes of the Republic (6 part series documenting the fall of the Roman Empire, starting with the Gracchi Brothers)
- Thor's Angels (Single 4 hr long episode documenting how europe fell into the Dark Ages and then continues up to Charlemagne)
There are many more great free podcast's on his site (there are also great paid ones), but these are some of my favorites. You can also find his podcast's on any major podcast manager.