The Great Glasshouse is the architectural centrepiece of the garden, and contains botanic specimens from Mediterranean climates around the world. It is sited on the top of a low hill and is landscaped to allow only the glazed roof to be visible above the surrounding gardens.
Other features of this Millennium Commission funded project included:
- creation of the garden landscape including visitor facilities, circulation routes and infrastructure services
- refurbishment of former stables into offices, shops, cafeteria and gallery spaces
- gatehouse, parking and access roads
- biomass energy generation
- nursery greenhouses
- creation of water features
- restoration of lakes
The glasshouse roof structure has spans of 99 and 53 metres on the long and short axes respectively. 24 tubular trusses carry the roof loads to the perimeter support walls. There are 785 glazing panels of 18mm thick laminated glass of which the largest are 4 metres x 1.5 metres, 147 of these are computer controlled to regulate the internal climate. A particular feature of the main roof arches is the stainless steel ball and socket joint. This neat detail allows the roof to ‘breathe’ in and out as it heats up and cools down or absorbs wind gusts, without transferring forces into the support structure.
Inside the glasshouse, a deep canyon of sculpted sandstone has been created using anchored retaining walls.