This is a hidden gem, a short trip from Oslo, for anyone who is interested in astronomy, science, nature and history. The location is set on a hilltop above Harestua, with beautiful scenery and good hiking opportunities in the forest.
The place has played a significant role in Norwegian astronomy since it was built in the fifties, and was at one point among the leading sun observatories in Europe. It was one of the first observatories to combine visual and radio telescope images. Most of the equipment is still in use, including the sun telescope and spectrometer.
It has a rich history, which involves being used as a satellite monitoring station during the Cold War. The camera was removed by the US, but the observation site now houses other telescopes including one with a rich history of its own dating back to WW II.
It is worthwhile checking their website before visiting, because they arrange different types of events throughout the year. If you visit when the place is staffed you will meet very friendly, enthusiastic and knowledgeable people. It has been privately owned and run since the University of Oslo decided to stop funding a few years back.
We visited Solobservatoriet on an open evening event in May. It's easily accessible by car (the gate will be open when they have special events), bike or walking from the Harestua train stop. They offer school excursions and events for children.
If you are interested in science and astronomy in particular, this is well worth a visit.