Stjerneborg ("Star Castle" in English) 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 Stellæburgus in Latin. Both the Danish and Latin names mean "castle of the stars".

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.

Click on the schematic for more details on the function of the various chambers.

Other articles related to "stjerneborg":

Uraniborg - History
... The result was Stjerneborg ("castle of the stars"), a smaller site built entirely at ground level and dedicated purely to observations (there was no "house") ... Christian IV of Denmark, Tycho abandoned Hven in 1597 and both Uraniborg and Stjerneborg were destroyed shortly after Tycho's death ... Stjerneborg was the subject of archaeological excavations during the 1950s, resulting in the restoration of the observatory ...