Okay, saw the film, …its actually a pretty simple effect (well, if you have the cash for the toys), they’ve used a motion control camera rig (indeed a big crane rig for the outside shot as they wander up to the church) and have simply done a couple of passes, one with the two main characters, then at least one other with people in period costume, ….then added some matte painting elements (as I explained above), then put a treatment over the old style extras. They may have done the crowd passes on a greenscreen stage using the same camera data on a motion control similar camera rig in order to easily isolate them for the treatment, likewise they might have had a greenscreen in situ for Tom Hanks and co to walk in front of for the initial part of that crane shot so the matte paintings could easily be inserted behind, …but having said that, I don’t think the reveals of the old archetecture ever cross their bodies, so it probably wasn’t necesary.
There you go.