It has been around since before 6,000BC, the Ancient Egyptians used a version of it and so did the Romans. Nowadays it is the most common man-made building material in the world, used for some of the planet's biggest engineering projects - and some of the smallest. It has not always been loved by the public but architects and designers see both practicality and beauty. There is also an environmental issue - the production of concrete has a major environmental impact. So what of its future? Bridget Kendall explores concrete with architect Anupama Kundoo, design critic and writer Stephen Bayley and engineer and scientist professor Paulo Monteiro. (Photo: The ceiling of the Pantheon in Rome is an example of Roman concrete construction. Credit: Getty Images)