Complex sentence: In 1907 this early open air museum, the world's first, was merged with the Norwegian Museum of Cultural History, which now manages the stave church, still nominally the property of the reigning monarch.
Split into simpler sentences: In 1907 this early open air museum, the world's first, was merged with the Norwegian Museum of Cultural History, which now manages the stave church. The church, however, is still nominally the property of the reigning monarch.