Complex sentence: The smallest and oldest is the Mariakirke, a single nave church built in the Romanesque style, but the neighboring Nikolaikirke is a three-naved basilica, probably inspired by the construction of the Halvardskirke in Oslo.
Split into simpler sentences: The smallest and oldest is the Mariakirke, a single nave church built in the Romanesque style. The neighboring Nikolaikirke is a three-isled basilica, probably inspired by the construction of the Halvardskirke in Oslo.