I remember reading a story about 15 years ago about a man driving early in the morning down a rural road and suddenly going through a "time portal" and ending up in 4th Century (or there abouts) England. He builds his home there including a sauna and rescues the granddaughter of another accidental time traveler from the 1960's. It even had a sequel, although, that wasn't as good. I'd love to reread the original if anyone knows the name of it. I always thought it would make a great movie.