Due to DNA testing, in a round about way, we have probably solved the brick wall of our ancestor Lars Monsen who was born in the Bergen area and lived in Kristiansand, Norway. His great-grandson Lauritz (later Lawrence Josiah Munson), my grandfather, came to Brooklyn, NY, with his family when he was six. That story is posted on this page about the Monsens at my family history site.
Lars Monsen had been our brick wall for a long time since it is a common name in the Bergen area although not, we thought, in southern Norway. Well it turns out there really were two men named Lars Monsen in Kristiansand at that time. One was Lars Monsen Suldahl (thus from Suldahl) and ours was Lars Monsen or Mognsen Aastvedt from Eidsvaag (just north of Bergen)
Here is the story. Dad matched almost 6000 people at 12 markers on the family tree DNA site. So I used the Ysearch site to look for only Bergen area matches. I contacted those two people and heard back from one. Next we both upgraded to 37 markers to see if we still matched. In the meantime our match, Sigmund, posted some queries in the best Norwegian forums for Bergen and Kristiansand areas and the local historian/genealogy experts weighed in and found Lars.