El Cantar del mío Cid by Ana María Moix is the adaptation of the epic medieval Castilian Spanish poem of such name https://en.wikipedia.org/wiki/Cantar_de_mio_Cid.
I haven’t read the original poem, and quite frankly, I think I would have a hard time fully understanding it, given of it’s archaic speech. However an interesting thing, is that I know the entire synopsis of the poem, as well as most of the contents of the poem itself. To add more, there was time were I would literally go to sleep listening to the poem at night! It’s really fascination that an archaic Castilian Spanish sounds more like modern Italian, than modern Spanish to me, but I digress.
Needless to say coming into this book, I had a good high-level knowledge of the poem, as well as a good high-level knowledge of the actual real historical context of the famous knight Rodrigo Díaz de Vivar, “El Cid”. This book is really good! The more novel approach was written extremely well. Anyone who doesn’t know the history of El Cid can easily pickup this book and not have a problem understanding the story. Thus said, the poem and some of the characters in it are completely fiction. This book should NOT be treated as a history book, but rather a historical novel. While the majority of characters are real historical figures, however a significant amount of portions of the events on this book are pure fiction. Making it a very good novel, but not an accurate historical retelling. Thus said, I’d still recommend this book! Especially if you want to know why “El Cid” is seen as a folk hero in the Hispanic world.