Stjerneborg (Star Castle) was Tycho Brahe's underground observatory next to his palace-observatory Uraniborg, located on the island of Hven in Oresund. Tycho Brahe built it circa 1581. He writes: "My purpose was partly to have placed some of the most important instruments securely and firmly in order that they should not be exposed to the disturbing influence of the wind, and should be easier to use, partly to separate my collaborators when there were several with me at the same time, and have some of them make observations in the castle itself, others in these cellars, in order that they should not get in the way of each other or compare their observations before I wanted this." He named it Stiernburg in vernacular or Stellæburgusin Latin.
The underground portions of the observatory were excavated in the 1950s and are today fitted with a roof approximating the original one. The chambers now house a multimedia show open to the public.References:
Medvedgrad is a medieval fortified town located on the south slopes of Medvednica mountain, approximately halfway from the Croatian capital Zagreb to the mountain top Sljeme. For defensive purposes it was built on a hill, Mali Plazur, that is a spur of the main ridge of the mountain that overlooks the city. On a clear day the castle can be seen from far away, especially the high main tower. Below the main tower of the castle is Oltar Domovine (Altar of the homeland) which is dedicated to Croatian soldiers killed in the Croatian War of Independence.
In 1242, Mongols invaded Zagreb. The city was destroyed and burned to the ground. This prompted the building of Medvedgrad. Encouraged by Pope Innocent IV, Philip Türje, bishop of Zagreb, built the fortress between 1249 and 1254. It was later owned by bans of Slavonia. Notable Croatian and Hungarian poet and ban of Slavonia Janus Pannonius (Ivan Česmički) died in the Medvedgrad castle on March 27, 1472.
The last Medvedgrad owners and inhabitants was the Gregorijanec family, who gained possession of Medvedgrad in 1562. In 1574, the walls of Medvedgrad were reinforced, but after the 1590 Neulengbach earthquake, the fortress was heavily damaged and ultimately abandoned. It remained in ruins until the late 20th century, when it was partly restored and now offers a panoramic view of the city from an altitude of over 500 meters.