The reinforced concrete was so massive that some structures survived the Nazis' demolition work Remote, hidden in dense forest, protected by nearby lakes and marshes - the Wolf's Lair in Poland was a secure headquarters for Adolf Hitler in World War Two.
![Wolf's Lair: Will Hitler HQ makeover create a Nazi theme park?](https://cdn-ak-scissors.b.st-hatena.com/image/square/c4d7a31fc3fabfa962ddc0bcdf0b573801dd6b34/height=288;version=1;width=512/https%3A%2F%2Fichef.bbci.co.uk%2Fnews%2F1024%2Fbranded_news%2F30E8%2Fproduction%2F_108102521_374aa3b7-4745-402f-8c14-542544cc25df.jpg)