What will buildings look like in the future?
When Roald Dahl imagined a chocolate factory that would appeal to children, and even to adults, he set the bar quite high for "intelligent" buildings and edible architecture.
Wonka's factory housed not only a lake of caramel and a mountain made of fudge, but a glass lift that could take you anywhere you wanted.
Architects will always push the boundaries in imagining how our homes and offices will look in the future, and their self-cleaning, self-healing and edible buildings are not so far from what the children's author dreamt up.
The increasing use of Wi-Fi-enabled products, combined with rapid developments in building materials, is bringing the future to life.
Professor Derek Clements-Croome, of the University of Reading, says an intelligent building is one that is responsive to the needs of people and organisations.
"An igloo is intelligent for what it does," he says. "The challenge of the 21st century is selecting what is appropriate. There is so much innovation available now.
"Buildings are becoming more organic - you will be able to have something more like a conversation with a building."
So the buildings of the future could have walls that repair themselves, self-cleaning windows, carbon-consuming cladding and even lunch growing up the walls.
New technologies and building techniques have been around for some time but are now assuming more importance because of the need to make buildings energy efficient and sustainable.
Even in regions where energy is cheap and plentiful, such as the Arabian Gulf, there is pressure to make buildings more comfortable and functional for those who live and work in them.
Also, the owners of buildings are increasingly looking at what it costs to run and maintain a property over its lifetime, as well as the cost of construction.
Intelligent buildings may cost about 6 per cent more to build, but they are healthier, productivity is higher, they are more sustainable, have higher rental value, less staff churn and lower running costs, Prof Clements-Croome says.
"All this means any extra costs is recovered in about two to three years," he adds.
Arup, an engineering and design consultancy, is working with businesses to try to design the best workspaces to meet their rapidly changing needs. To help it do this, it allows its consultants' imaginations to run riot in thinking about buildings of the future.
Arup predicts that by 2050, cities will grow vertically and towers will have walls that repair themselves, windows that darken if it is bright, algae growing on the walls that consumes carbon dioxide alongside food we can harvest - think edible leaves and fruits. It is possible such towers will even have robots to clean it all.
But the immediate challenges businesses face are more mundane.
"There is an increasing need for creativity and collaboration. Businesses are addressing problems that are going to be more complex and need a faster response time," says Rebecca Goldberg, an associate at Arup. "Increasingly, they will need to pull different groups of people together quickly, so we are designing work places to support that. There are open desk spaces, breakout areas, cafes and quiet spaces.
"People may not have the ownership of one desk, but they may be given more choice about how and where they work and what IT they use."
Neil Pennell, the head of sustainability and engineering at Land Securities, a major British property developer, who recently chaired a conference on the office of the future, agrees the primary feature of an intelligent building will be that it can respond to changes in working practices.
"There are more and more choices out there for architects and developers, from the type of materials that are used to the IT systems that are installed," he says. "But it all needs to be focused on the needs of people and be adaptable because the world of work is changing very quickly."
Previously, intelligent heating and cooling systems in buildings tended to be bespoke. Now, with the spread of Wi-Fi, lots of devices - for instance to control the colour of walls, the shades on windows, the air temperature - can run through the same IT system.
Meanwhile, nano technology and biotechnology is helping to tailor building materials to the environment. Nano-coatings can respond to the presence of a person, so a workspace is illuminated when you arrive or a predetermined microclimate is triggered for a meeting room.
Technicians have developed self-cleaning concrete - now used on Air France's headquarters at Charles De Gaulle airport in Paris. The Air France building uses titanium dioxide to break down unsightly pollution into its chemical constituents, which rain then washes off the exterior. Self-repairing concrete is being developed for commercial use at a Dutch university.
Also, there is pressure to push buildings beyond mere sustainability. It is not enough simply for a building to be carbon or energy-neutral. In the future, buildings will be an active part of the grid - either producing solar or wind energy or consuming carbon and replacing it with oxygen.
But the biggest change to the future of the office may be more familiar than we think. With super-fast broadband more cheaply and easily available, it is likely that an increasing number of people will work from home, making many offices redundant.
Arup maintains that workplaces have advantages still. The incidental meeting in the staff canteen - lovingly redesigned as a funky, Wi Fi enabled chill-out space - is as necessary as ever, to spark ideas and productivity, argue the engineers and their clients.
Plants have been used in architecture for thousands of years. Islamic architecture, in particular, has used quiet spaces to cool buildings naturally.
In recent years, architects such as Ken Yeang, from Malaysia, have pioneered a form of green architecture and master-planning that uses climate-responsive principles to build low-energy buildings.
Living façades, where plants are grown up the sides of a building, are an extension of this philosophy. The plants grow up the walls, absorbing carbon dioxide and releasing oxygen as they go.
In Japan, Kyocera, an electronics maker, has been using so-called "green curtains" since 2007 to help keep buildings stay cool. Climbing plants - morning glory and goya - are trained up the sides of the building. The plants reduce carbon dioxide emissions and produce a harvest of vegetables that can be found on the menu at the staff cafeteria.
Elsewhere, architects are looking at the cooling properties and CO2 absorption of algae.
Buildings could be wrapped in an algae "tube" into which gaseous waste products from the building are pumped.
Once the algae has cleansed the building, it could be harvested for bio-energy generation, effectively turning office buildings into mini-power plants.
This is already happening at the Red Hawk power plant in Arizona.
Meanwhile, in Mumbai, a firm is turning algae grown on fences wrapped around a building into cosmetics. It is but a short step further to suggest edible algae or plants such as spirulina could be grown on walls and harvested for consumption.
More prosaically, in Todmorden, a market town in West Yorkshire, the community has begun growing fruit and vegetables everywhere it can, including an "edible" tow path, beside the canal and outside the police station. It's not quite edible buildings - but the founders call it an edible landscape.
"This is a movement for everyone. If you eat, you're in," says Pam Warhurst, the co-founder of the Incredible Edible community initiative, which is encouraging people to choose local food and take care of their environment and community.
After all, for centuries we have grown vines, fruit, vegetables such as beans and plants such as sunflowers, up walls - helping nature to get to the light and warmth, while simultaneously cooling buildings.