The Nidaros Cathedral was first constructed as a very small chapel under which King Olaf II Haraldsson (995-1030), later known as St. Olaf, was buried about 1070.  He was recognized as the person who brought Christianity to Norway.  His assassination, seen as martyrdom for the cause,  was promoted by the Catholic church to help with the conversion of the heathen north.  As more and more pilgrim came to Trondheim along the St. Olaf's Way, the cathedral was expanded using the Medieval or Gothic style of architecture.  A fire burned almost half the building down in the late 1327 again in 1531 and in 1719 it was struck by lightning and laid in ruin.  Only Norwegian independence made it possible to rebuild the structure in the same style in after May 17, 1814 (Syttende Mai).   It is recognized as the National Cathedral of Norway and used for important national celebrations. 

Although dedicated to St. Olaf, the cathedral was not built for a couple hundred years after his death. King Olaf II Haraldsson was not the most lovable person and in fact seems to have been quite vicious to those that opposed him and his goal to convert or control his countrymen.  He may not have been all that committed to Christianity as it may appear.  He was sainted a year after his death. Pilgrimage to the Cathedral seems to have been very popular through to about 1349 when the Black Plague devastated Norway, Sweden and Russia. Many stave churches fell into ruin during this period and population recovery was very slow. The popularity of the pilgrimage was renounced for it Catholic origin during the Reformation and the adoption of Lutheranism.  Only more recently has the trail returned to popularity.  The trail that cuts through the Hamar region actually goes across several of my families farms.  St. Olaf's way is a trail system still maintained and even more popular now than it has been for many years due to the interest in hiking and physical health.  It runs from Oslo through Hamar and Lillehammer to Trondheim for some 400 miles.  [wikipedia.com]

This partial map of Løten area comes from 1862
several farms on which our relatives have lived  back to the 1500's
[Norgeskart historical map - Amtskart]