Records of the Grand Historian: Qin Dynasty (ca. -100, tr 1993)
by Sima Qian (ca. -100), tr Burton Watson (1925-)
This is (part of) one of the works recommended by Kenneth Rexroth in Classics Revisited, and so has been on my list for many years. Watson has translated parts of the work and published them in digestible chunks, rather than the entire work.
I think Rexroth was interested in Sima Qian as among the earliest historians; he also likes Thucydides. Sima Qian wrote of the dynasties for which he had records, or at least stories, and certainly felt he was writing for posterity. He suffered castration for some crime, and says that he should have committed suicide rather than suffer this humiliating punishment; but he felt it was more important to complete his project.
The actual incidents and the insight they give to the times are not as interesting to me as the fact that a man of this time was able to take such an approach. He clearly had insight into the minds and ways of the ruling class of his time.