Nidarosdomen/St Olav cathedral, Trondheim
I don't normally recommend cemetery walks to VTers but the cemetery at Trondheim Cathedral has so many beautiful sculptured grave markers that it merits a visit. Taking a walk in the quiet but green grounds make it a strangely spiritual experience.
When I visited Trondheim this autumn, I found some archeological excavations going on. Not sure how long the will last, but it was definitely interesting to watch.