In Sonnenborgh several worlds come together: a museum, an observatory and a medieval bastion. This small museum focuses on meteorology and the sun. You can experience first-hand how wind is created and why it's so difficult to accurately predict the weather. A look into the bastion will teach you that this 16th-century fortress has been enormously significant for the development of the city of Utrecht and many enemies were kept at bay from here. Sonnenborgh has five large telescopes directed at the skies and special stargazing nights are organised for a peek into the universe. An extraordinarily impressive library containing books on astronomy, meteorology and space research is also available.