BBC News - How to build a medieval castle (http://news.bbc.co.uk/1/hi/world/europe/10435388.stm#id10430000/10435300/10435388)
Deep in the forests of central France, an unusual architectural experiment is halfway to completion, as a team of masons replicates in painstaking detail the construction of an entire medieval castle.
The chateau de Guedelon was started in 1998, after local landowner Michel Guyot wondered if it would be possible to build a castle from scratch using only contemporary tools and materials.
Today the walls are rising gradually from the red Burgundy clay, as guide Sarah Preston explained to Hugh Schofield.