[drofgnal]

The first book I thought of was Noah Gordon's Physician. From Amazon:

Spoiler:

When nine-year-old Rob Cole felt the life force slipping from his mother's hand he could not foresee that this terrifying awareness of impending death was a gift that would lead him from the familiar life of 11th-century London to small villages throughout England and finally to the medical school at Ispahan. Though apprenticed to an itinerant barber surgeon, it is the dazzling surgery of a Jewish physician trained by the legendary Persian physician Avicenna that inspires him to accept his gift and to commit his life to healing by studying at Avicenna's school. Despite the ban on Christian students, Rob goes there, disguising himself as a Jew to gain admission. Gordon has written an adventurous and inspiring tale of a quest for medical knowledge pursued in a violent world full of superstition and prejudice. Recommended. Literary Guild alternate. Cynthia Johnson Whealler, Cary Memorial Lib., Lexington, Mass.

I'm not nominating this, I've read it so I'm just putting it out there if someone else wants to. Warning, It's quite lengthy. 838 pages.