A man works at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, September 13, 2016. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century, and has been in construction since June 1997 when the first stone was laid. Picture taken September 13, 2016. REUTERS/Jacky Naegelen - RTSNQ77

Guillaume Glotin, mason at the site since 2006, poses in his workshop at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, October 29, 2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture taken October 29, 2013. REUTERS/Jacky Naegelen

View of the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, October 29, 2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture taken October 29, 2013. REUTERS/Jacky Naegelen

A view of the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, September 13, 2016. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century, and has been in construction since June 1997 when the first stone was laid. Picture taken September 13, 2016. REUTERS/Jacky Naegelen - RTSNQ6I

A worker walks in a winch drum at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, September 13, 2016. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century, and has been in construction since June 1997 when the first stone was laid. Picture taken September 13, 2016. REUTERS/Jacky Naegelen - RTSNQ79

Colour test are seen on a wall of the Chateau de Guedelon near Treigny in the Burgundy region of France October 29, 2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture taken October 29, 2013. REUTERS/Jacky Naegelen

View of the frontage of the Chateau de Guedelon at the construction site near Treigny in the Burgundy region of France October 29, 2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture taken October 29, 2013. REUTERS/Jacky Naegelen

Women work at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, September 13, 2016. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century, and has been in construction since June 1997 when the first stone was laid. Picture taken September 13, 2016. REUTERS/Jacky Naegelen - RTSNQ6R

Clement Guerard, blacksmith at the site since 1999, poses in his workshop at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, October 29, 2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture taken October 29, 2013. REUTERS/Jacky Naegelen

View of the castle bedroom at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, October 29, 2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture taken October 29, 2013. REUTERS/Jacky Naegelen

A view of the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, September 13, 2016. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century, and has been in construction since June 1997 when the first stone was laid. Picture taken September 13, 2016. REUTERS/Jacky Naegelen - RTSNQ5M

Stonecutter and massons work at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, September 13, 2016. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century, and has been in construction since June 1997 when the first stone was laid. Picture taken September 13, 2016. REUTERS/Jacky Naegelen - RTSNQ7G

Thierry Baupain, woodcutter at the site since 1999, poses in his workshop at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, October 29, 2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture taken October 29, 2013. REUTERS/Jacky Naegelen

A view of the blue print of the Chateau de Guedelon is seen at the construction site near Treigny in the Burgundy region of France October 29,2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture taken October 29, 2013. REUTERS/Jacky Naegelen

A blue print and a model of the Chateau de Guedelon are displayed at the construction site near Treigny in the Burgundy region of France October 29, 2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture taken 29, 2013. REUTERS/Jacky Naegelen

A view of the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, September 13, 2016. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century, and has been in construction since June 1997 when the first stone was laid. Picture taken September 13, 2016. REUTERS/Jacky Naegelen - RTSNQ6K

Eugene Kedadra, stonecutter at the site since 1999, poses in his workshop at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, October 29, 2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture taken October 29, 2013. REUTERS/Jacky Naegelen

Stonecutters tools are seen at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, October 29, 2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture taken October 29, 2013. REUTERS/Jacky Naegelen

A stonecutter works at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, September 13, 2016. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century, and has been in construction since June 1997 when the first stone was laid. Picture taken September 13, 2016. REUTERS/Jacky Naegelen - RTSNQ5N

Workers carry stones at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, September 13, 2016. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century, and has been in construction since June 1997 when the first stone was laid. Picture taken September 13, 2016. REUTERS/Jacky Naegelen - RTSNQ6L

Bruno Feval, tiler at the site since 2004, poses in his workshop at the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, October 29, 2013. The Guedelon castle is a typical French medieval chateau-fort being built using the techniques, materials and rules of the 13th Century. It is the brainchild of Michel Guyot, local landowner, and business woman Maryline Martin, now site's managing director, and has been in construction since June 1997 when the first stone was laid. What started out as an eccentric project is now an established enterprise, employing 65 people and drawing in visitors from around Europe every year. The medieval castle will be finished around 2030. Picture October 29, 2013. REUTERS/Jacky Naegelen