The Bergen Domkirke, or Cathedral, is found in the city center and was first mentioned in literature as far back as 1181, meaning it is one of the oldest buildings in Norway. It has burned down and been rebuilt several times, but visitors staying in hotels in Bergen today can see what mostly resembles the original structure. The decidedly rococo interior, for example, has been renovated to have its original more Medieval appearance. You will no longer find the Franciscan monastery that was near the church and incorporated into it in the 12th century. What you may find interesting is that this is now the seat of the Diocese of Bjørgvin.
If you are visiting Bergen, the Domkirke is not the only sight you should see. Near this fantastic tourist attraction, you can also find the Hanseatic Museum and should definitely stop by the Fisketorget (fish market) to grab some fresh fish. The latter is practically next door to the cathedral.