Complex sentence: They then travelled with the dog to Jungfraujoch, home to Europe's highest railway station, and deliver their St. Bernard to a mountain rescue guide and then were allowed to search the Sphinx Observatory for their next clue.
Split into simpler sentences: They then travelled with the dog to Jungfraujoch, home to Europe's highest railway station, and delivered their St. Bernard to a mountain rescue guide. Then they were allowed to search the Sphinx Observatory for their next clue.