Dr Hans-Ulrich Niemitz's The Phantom Time Hypothesis blows my mind a little bit. Basically, you know in Almost Famous, when William finds out he's actually two years younger than he thought he was, because his mum's been lying to him for his whole life? Well, it's like that, but instead of an eleven-year old, it's ALL OF HISTORY. Apparently 300 years' worth of middle ages didn't actually happen, and were just recorded due to a clerical error or something.
It's probably baloney, but at least it's pretty baloney, thanks to the above visualisation of the theory by Austrian designer Michael Paukner.