Raven on St Magnus' Cathedral

I've noticed a raven flying about the town for weeks, and heard one calling from the cathedral steeple one dark, foggy morning, but today I saw two on the steeple and they were calling loudly. It looked pretty much like they were claiming the spot for a nest.  That would be pretty good, though there are tours of the cathedral which include going out where the birds might nest. But they are very early nesters and perhaps the tour could avoid the spot until the nest was done with. That would be well before the busy season. Maybe it could be watched with a nest-cam. But I may be counting my ravens before they're hatched.