Found a right gem for anyone interested in the history of WW2, while on a visit to france recently.

Le Blockhaus l'Éperlecques.

One of the original fixed Launch sites for the V2 rocket, built by slave Labour. If anyone finds themself in the Calais area for any reason it is well worth a visit.

The true tragedy though is not only was slave labour used in its construction, but many of them were killed during the numerous Allied Bombings that unsuccessfully tried to destroy it.

http://www.leblockhaus.com/intro.htm