Norwegian stave churches are an architectural representation of the merging of Roman Catholicism and Norse Paganism in the 13th and 14th centuries A.D. In 1015, King Olav Haraldsson made Christianity the official religion of Norway. It took his death 15 years later for the trend to set. Once a majority of the Norwegian pagans converted, the country was faced with a new problem: no churches.
The Vikings were incredible shipmakers, architects, and wood-carvers who had been perfecting these trades for thousands of years. To build the foundation for their homes, they would place wooden posts called staves into holes in the ground. Naturally, their first churches were constructed in the same fashion. Unlike the homes, however, the churches were still being used a hundred years later when the corner posts of such constructions rotted away, leaving the structure to tumble. Viking builders were met with the problem of longevity, a challenge to which they were quick to rise. Now the staves were placed on wooden beams and sills, keeping them off the ground and away from damp, rot, and eventual collapse.
After years of refinement, the stave churches became incredible works of architecture. They are almost entirely made of wood, and rise into the sky with steep, shingled rooftops in a pagoda formation. Few windows allow light into the building, so worship was done by candlelight or in quiet afternoon shadows. The intricate ornamentation is breathtaking; carvings of dragons and other animals embedded in the woodwork tell stories of pagan tradition and Norse legend. Even more incredible is the crafstmanship of the building itself. If you tour a Norwegian stave church, you can see the dovetail joints, braces, and masts that keep the church standing. The precision and detail were achieved without nails and screws, stone or iron.
Although upwards of 1200 churches were built in medieval Norway, only a few stave churches still stand in the Norwegian landscape. Many fell because of poor maintenance and natural forces; others fell because of religious intolerance. There are between twenty and thirty stave churches in tact today, protected by the Society for the Preservation of Norwegian Ancient Monuments.
Information provided by http://www.hjemkomst-center.com/church/main.htm and Norway, a tourist book published by SFG.