Ever wonder how the Roman Colosseum was constructed? How about the Egyptian pyramids? `Time Scanners' uses 3-D laser-scanning technology to reveal the secrets of how these and other engineering marvels were built. Dallas Campbell presents the programme, which uses the latest research tools and visual mapping to reveal the mysteries behind some of the world's most recognizable buildings. Structural engineer Steve Burrows.- the man behind Beijing's Olympic Stadium and other famous structures - leads the investigations, joined by laser-scanning experts from the Universitry of Arkansas. Given unprecedented access, Burrows and his crew explore, scan and digitally analyse the architectural achievements.