Looks military, could be EW or SAM site.
Military site
No Thumbnail
© Bing Maps
By nico @ 2012-11-21 18:09:44
militaryman
@ 2012-11-21 18:42:49
Underground fuel depot. those are tankers, it is kept separate from base in case of explosion. It is weird though that there is no direct road the the runway/taxiways.
nico
@ 2012-11-21 18:49:38
Probably right, looking thru the internet sites, it was said that a SAM P /ASTOR SAM battery was located at Mont de Marsan, thought it could be that.