Lest Darkness Fall is an alternative history science fiction novel written in 1939 by author L. Sprague de Camp. The book is often considered one of the best examples of the alternative history genre.
Lest Darkness Fall is along the same lines as Mark Twain's A Connecticut Yankee in King Arthur's Court. Archaeologist Martin Padway is inspecting the Pantheon in Rome during the early World War II era. A thunderstorm arrives, lightning cracks, and he finds himself transported to 6th century Rome.
