A world where, instead of aging in years, the people age in knowledge. So, instead of dying once a general age was reached, they die once they achieve a certain amount of knowledge. A man could live forever if he never learned anything, or could die after reading a few choice books. Of course, the knowledge of the land would be regulated, like medical drugs.
What if dragon-sightings and evidence of such was treated with the same skepticism and mockery as modern UFO sightings? More for a low magic world where dragons 'dont' exist.