Wikipedia
Uraniborg
Uraniborg (, ) was a Danish astronomical observatory and alchemical laboratory established and operated by Tycho Brahe. It was built on Hven, an island in the Øresund between Zealand and Scania, which at that time was part of Denmark. Shortly after its construction, the observatory was expanded with an underground facility, Stjerneborg, on an adjacent site.
Tycho abandoned Uranienborg and Stjerneborg in 1597 after he fell out of favor with the Danish king, and he left the country. The institution was destroyed in 1601 after Tycho's death. Hven was later lost to Sweden. The Round Tower in Copenhagen was inaugurated in 1642 as a replacement for Uraniborg's astronomical functions. Uraniborg's grounds are currently being restored.