Very soon we'll be joining a Viking cruise which calls at Civitavecchia, where some guests will disembark and others will join for the next cruise.  No excursions have been offered in advance, though I guess maybe they will be offered for those staying onboard for both cruises.  We've been to Rome before and therefore we've been thinking we might explore the local area.  Have any of you done this?  And do Viking run a shuttle bus into the town centre?