Railway historian Tim Dunn and Siddy Holloway from the London Transport Museum explore hidden areas of the London Underground that—despite being just feet away from where millions of people regularly travel—hardly anyone knows about. The pair will explore abandoned tunnels, secret bunkers and hidden staircases that have been concealed from public view for years.

Railway expert and train enthusiast Tim Dunn explores the stunning architecture that lines the railway network in `The Architecture the Railways Built'. He visits stations made up of simple stone buildings, decorative Victorian grandeur, and striking glass and concrete structures, but he doesn't stop at visiting stations, as he explores every structure which owes its existence to the railway, including viaducts, railway hotels, tunnels, and the less obvious buildings such as homes, swimming pools, and Turkish baths.

The Channel Tunnel linking Britain with France is one of the seven wonders of the modern world but what did it take to build the longest undersea tunnel ever constructed? We hear from the men and women, who built this engineering marvel. Massive tunnel boring machines gnawed their way through rock and chalk, digging not one tunnel but three; two rail tunnels and a service tunnel. This was a project that would be privately financed; not a penny of public money would be spent on the tunnel. Business would have to put up all the money and take all the risks. This was also a project that was blighted by flood, fire, tragic loss of life and financial bust ups. Today, it stands as an engineering triumph and a testament to what can be achieved when two nations, Britain and France put aside their historic differences and work together.