Author Dr Gavin Francis passes the new Queensferry Crossing every morning on his way to work. When it is finished in May 2017, it will be the largest balanced cantilever ever built. Gavin believes it is the most impressive structure under construction in these islands today.

This week's Essays are part of the 70th birthday celebrations of the Third Programme: the network discussed architecture from its earliest days, covering both new initiatives and historic buildings, most notably in talks by Nikolaus Pevsner.

Producer Clare Walker.