Structural engineer Steve Burrows scans the sacred Inca city of Machu Picchu using 3D laser technology. His three main questions: How did the Inca build a city atop a mountain? How were the terraces constructed? And how did they supply water to the city?

Time Scanners: Macchu Picchu

TV presenter Dallas Campbell, engineer Professor Danielle George and engineer Dr Hugh Hunt re-create the opening of the BBC's television service on 2 November 1936. This involves building the mechanical flying-spot cameras that were used by Baird's system.