Lithuanian:

www.army.lt
http://digeriai.net
http://tvirtove.kaunas.lt/
www.vilniusbunkers.narod.ru

The rest:

www.infiltration.org
www.maginot.org
www.bunkerforschung.de
www.atlantikwall.net
www.dolomitenfreunde.at
sovietkaput.free.fr
www.ctrebova.cz/co/
josecadaveira.tripod.com/militaryruins
Femöre fort in Sweden
Forty Krakow
Atlas rocket silo being converted into an underground house
www.secreturbanexplorationninjamafia.com