Tycho's observatory of Uraniborg. 17th-century illustration of the roof of the observatory of Uraniborg, built on the island of Hven between 1576 and 1580 for Danish astronomer Tycho Brahe (1546-1601). Named for the Greek muse of astronomy, it was used to make the most accurate naked-eye measurements yet made of the position of the stars. The main building was about 15 metres on each side, with three floors and a central tower rising from the roof. This artwork is from the 1603 edition of Tycho's 'De Mundi Aetherei Recentioribus Phaenomenis Liber Secundus', originally published in 1588.