The Nidaros Cathedral was built on the site of the burial of King Olaf II Haraldsson (995-1030) later known as St. Olaf.  He was killed a few miles north of Trondheim and buried initially at a site on the grounds of the present cathedral.  As Olaf became known and eventually sainted by the Catholic Church a larger cathedral was constructed.  It was destroyed by fire a couple of times over the centuries after lightning strikes. The present rebuilding was finished for the anniversary of the independence of Norway in 1814 after the building sat in ruins for almost a hundred years. The burial place of St. Olaf is unknown but somewhere on the grounds of the cathedral.  It was known as the place of religious pilgrimage for many years before the plague devastated the country about 1349. Well worn trails were established from Oslo to Trondheim, a distance of about 400 miles.  Although it fell into disuse it has become important again to the youth of the country for its physical demands.  It is presently a National monument and symbol of Norway.

source:

Christenson, Elroy.  photos 2016
Nor. Nat. Archives/Arkivverket Digitalarkivet  - http://arkivverket.no/Digitalarkivet
Stange Bygdebok, volumes 1- 6  - Hedmark Slektshistorielag - http://www.hedmarkslekt.no/Stangeboka for Bjornstad farm #55 wikipedia.com