The Time and Space project establishes a new centre for modern astronomy and a planetarium at the Royal Observatory, Greenwich. Set in Greenwich Park, at the centre of the World Heritage site, the southernmost buildings at the Royal Observatory have always been disconnected from the principal public spaces. This project transforms the late nineteenth century ‘South Building’, but also establishes a new landscape context, making it physically accessible and visually connected with the rest of the site. Set in this new landscape, the planetarium is a new addition to the collection of astronomical ‘instruments’ which make up the observatory. The planetarium is largely housed beneath the new landscape but its domed auditorium is enclosed by a tilted and truncated bronze cone, whose geometry is defined precisely by the relationship of its location, in latitude and longitude, to the universe it represents inside. Its axis is aligned with the North Star and, the inclined disc of its top is parallel with the equator, thus reflecting the northern hemisphere of the night sky.