Does anyone know a good book set in Late Antiquity / Dark Ages?

I'm looking for good historical novels set afte the fall of the Roman
Empire (476 BC) but before the rise of Charlemagne (late 700s),
preferrably in Western Europe.  Of course that's King Arthur's period,
but I'm not really looking for that.  If anyone can recommend
anything, I'd really appreciate it.

Thanks.

/Aaron