asy ▁and ▁bro th el . ▁ ▁In ▁ 1 9 2 8 ▁New ▁York ▁City , ▁Jack ▁K ri end ler ▁and ▁Charlie ▁Bern s ▁purchased ▁a ▁former ▁bord ello ▁and ▁converted ▁it ▁into ▁a ▁bar ▁and ▁restaurant ▁called ▁the ▁" 2 1 ▁Club ." ▁In ▁ 1 9 3 0 , ▁they ▁h ired ▁architect ▁Frank ▁Buch an an ▁to ▁design ▁a ▁secret ▁door ▁to ▁hide ▁the ▁ ▁liqu or ▁supply ▁in ▁the ▁cell ar , ▁as ▁the ▁place ▁was ▁converting ▁to ▁a ▁spe ake asy . ▁To ▁conce al ▁the ▁hidden ▁door ▁from ▁federal ▁prohib ition ▁agents , ▁Buch an an ▁designed ▁the ▁door ▁so ▁that ▁it ▁would ▁appear ▁to ▁be ▁solid ▁concrete ▁wall . ▁The ▁door , ▁which ▁we ighed ▁two ▁and ▁a ▁half ▁tons , ▁was ▁supported ▁by ▁massive ▁precision ▁h ing es ▁and ▁faced ▁with ▁a ▁concrete ▁sl ab . ▁The ▁secret ▁door ▁could ▁be ▁opened ▁only ▁by ▁inserting ▁an ▁ 1 8 " ▁length ▁of ▁wire ▁through ▁one ▁of ▁several ▁cra cks ▁in ▁the ▁concrete . ▁ ▁During ▁World ▁War ▁II , ▁British ▁Royal ▁Air ▁Force ▁officers ▁held ▁capt ive ▁in ▁Cold itz ▁Castle ▁built ▁a ▁false ▁wall ▁in ▁the ▁att ic ▁of ▁one ▁of ▁the ▁P OW ▁buildings , ▁to ▁hide ▁a ▁work shop ▁where ▁they ▁were ▁construct ing ▁a ▁gl ider ▁to ▁help ▁them ▁escape . ▁ ▁Gu err illa ▁war fare ▁f igh ters ▁have ▁used ▁t unn els ▁and ▁secret ▁pass ages ▁to ▁attack ▁their ▁enemies ▁without ▁being ▁captured ▁and ▁transport ▁arms