Most excellent program. I guess that now the tunnels at La Boisselle are closed for the foreseeable future I am very lucky at having been in them during the archaeological dig there. If they ever re-open then may I suggest that the cost of a visit to this part of France is worth every penny (or euro)! There are a few other mining/tunnelling sites in northern France and Belgium that do open to the public on occasions. You may wish to have a look at "The Durrand Group" website. At least we explore mines without the risk of being gassed or blown to bits!!!!