I recently read the novel Outlander by Diana Gabaldon (1991).
This novel by DG is a classic tale of unintentional time travel. British Army nurse Claire Randall steps through a time-warp door at a stone henge in 1946 and suddenly finds herself in the Scottish highlands of the mid-1700s.
The story details Claire's encounters (one of which is with a dastardly ancestor of her 20th century husband), challenges, relationships. and ethical dilemmas as she grapples with navigating life 200 years previous to her "real" life.
A great story, with lots of the typical novel faire - intrigue, politics, murder, love, life-struggles. A little more sexual content than suits my taste, but a cool story nonetheless.