|1843|| ||Proposed||Drawing showing conjectural restoration of the National Monument.|
|1949|| ||Alteration/conversion||Development proposed for Festival of Britain celebrations|
|1996||1997||Proposed||£15-20million scheme for a large self supporting all-glass structure as a landmark millenium project. Works to include refurbishment of the existing observatory complex, provision of a visitor centre, landscaping and public transport.|
The glass structure is designed to be interactive, with coloured laser displays to suit performances.