The best book I read this year was "Julian" by Gore Vidal. This is a thoroughly-researched historical fiction book about the Roman emperor Julian, the last pagan emperor of Rome. Thirty years before Julian rose to the throne, his grandfather Constantine the Great transformed Christianity from a persecuted sect practiced by a significant minority into the official religion of the state. In those thirty years, the ancient cults had mostly withered and died, their temples turned into churches or abandoned in disrepair.
Julian set out to revive the old religions and convert Rome away from Christianity. He was a bookish boy, a bit of a philosophy nerd. When he unexpectedly rose to a position of prominence, it turned out that he had a knack for military command which helped him gain popularity with the people and seize the emperorship.
I enjoyed this book because it gets you inside the head of people in a different time and place, with different thoughts and concerns than modern westerners. It also shows you how quickly the world can change. Julian lived in a time when thousands of years of tradition were changing quickly, in a blink of an eye by historical terms. These are great lessons to have in mind.