ina ' s ▁original ▁designs ▁were ▁intended ▁to ▁show ▁real ▁monuments , ▁for ▁political ▁reasons ▁the ▁bridge ▁and ▁the ▁window ▁are ▁merely ▁hypoth et ical ▁examples ▁of ▁the ▁architect ural ▁era . ▁ ▁Like ▁all ▁euro ▁notes , ▁the ▁€ 5 0 ▁note ▁shows ▁the ▁den om ination , ▁the ▁EU ▁flag , ▁the ▁signature ▁of ▁the ▁president ▁of ▁the ▁EC B , ▁the ▁initial s ▁of ▁the ▁EC B ▁in ▁the ▁different ▁EU ▁languages , ▁a ▁dep iction ▁of ▁EU ▁territ ories ▁over se as , ▁the ▁stars ▁from ▁the ▁EU ▁flag ▁and ▁various ▁security ▁features . ▁ ▁Security ▁features ▁( First ▁series ) ▁ ▁The ▁fifty ▁euro ▁note ▁contains ▁the ▁following ▁security ▁features : ▁▁ ▁Col our ▁changing ▁in k ▁used ▁on ▁the ▁numer al ▁located ▁on ▁the ▁back ▁of ▁the ▁note , ▁that ▁appears ▁to ▁change ▁colour ▁from ▁pur ple ▁to ▁brown , ▁when ▁the ▁note ▁is ▁t ilt ed . ▁ ▁A ▁see ▁through ▁number ▁printed ▁in ▁the ▁top ▁corner ▁of ▁the ▁note , ▁on ▁both ▁sides , ▁appear ▁combine ▁perfectly ▁to ▁form ▁the ▁value ▁numer al ▁when ▁held ▁against ▁the ▁light . ▁ ▁A ▁h olog ram , ▁used ▁on ▁the ▁note ▁which ▁appears ▁to ▁see ▁the ▁h olog ram ▁image ▁change ▁between ▁the ▁value ▁and ▁a ▁window ▁or ▁door way , ▁but ▁in ▁the ▁background , ▁it ▁appears ▁to ▁be ▁rain bow - col oured ▁concent ric ▁circles ▁of ▁micro - let ters ▁moving ▁from ▁the ▁centre ▁to ▁the ▁edges ▁of ▁the ▁patch . ▁▁ ▁A ▁E