There is number of sources about old norse paganism. The most important are the eddaic poetry and Snorri´s Edda. There are also runestones, written sources from non-norse observers, graves. Then there also is Toponomy, the study of placenames, many of which are religous and have survived until the modern day.

During the viking era (800-1050) the norse did not accumulate wealth in a way comparable to the other cultures you have studied. They did not have strong states, but were mostly tribal. Kings were relatively weak and their role mostly limited to military matters. They did not really have the resources to build grand and lasting temples. Also, worship was large conducted outdoors on natural sites.

We know from written sources that there were built "hof" which were temples, but they would have been built from soil and timber, rather than stone, and would not be well preserved into the modern day. After converting to christianity, churches would often be built on the temple site. Norwegian stave churches might have been somewhat inspired by pagan temple designs. Some remains have been found of the pagan hof in Uppsala.