▁the ▁line ▁of ▁the ▁castle ' s ▁former ▁eastern ▁walls . ▁The ▁entire ▁tunnel ▁is ▁v ault ed ▁and ▁built ▁in ▁Ne o - class ical ▁style . ▁ ▁History ▁Const ruction ▁of ▁the ▁Dark ▁Gate ▁started ▁in ▁ 1 8 2 4 ▁by ▁Alexander ▁Rud n ay , ▁Arch bishop ▁of ▁Es z ter gom , ▁two ▁years ▁after ▁the ▁foundation ▁stones ▁of ▁St . ▁Ad al bert ' s ▁Bas il ica ▁were ▁laid . ▁It ▁became ▁known ▁as ▁Dark ▁Gate ▁due ▁to ▁the ▁lack ▁of ▁light ing . ▁The ▁main ▁purpose ▁of ▁the ▁tunnel ▁was ▁to ▁directly ▁connect ▁the ▁Can onic ▁houses ▁with ▁the ▁Sem inary , ▁but ▁it ▁also ▁connect s ▁the ▁Sz ent gy ör g ym ez ő ▁neighborhood ▁with ▁dow nt own ▁Es z ter gom . ▁A bove ▁the ▁southern ▁entrance , ▁a ▁Latin ▁sign ▁car ved ▁in ▁red ▁mar ble ▁comm emor ates ▁Arch bishop ▁Rud n ay ▁and ▁the ▁year ▁of ▁construction : ▁" PR IN CE PS ▁PR IMA S ▁A LE X AN DER ▁A ▁R UD NA ▁MD CC C XX IV " ▁(" Pr ince ▁Pr imate ▁Alexander ▁Rud n ay ▁ 1 8 2 4 "). ▁From ▁both ▁sides ▁of ▁the ▁tunnel , ▁a ▁huge ▁ 3 7 0 0 ▁m ² ▁wine ▁cell ar ▁opens , ▁where ▁the ▁w ines ▁of ▁the ▁Arch di oc ese ▁of ▁Es z ter gom ▁were ▁kept . ▁ ▁During ▁the ▁ 1 9 5 6 ▁revolution , ▁significant ▁events ▁occurred