▁fort ▁constructed ▁during ▁the ▁F lav ian ▁period , ▁the ▁first ▁stone ▁cas tr um ▁at ▁Hal my ris ▁was ▁built ▁during ▁the ▁reign ▁of ▁the ▁em peror ▁Tra jan . ▁ ▁Although ▁the ▁original ▁layout ▁of ▁the ▁Tra jan ic ▁fort ▁is ▁largely ▁covered ▁by ▁later ▁re construct ive ▁phases , ▁the ▁plan ▁seems ▁to ▁have ▁been ▁indic ative ▁of ▁the ▁' typ ical ' ▁ 2 nd ▁century ▁layout ▁of ▁a ▁Roman ▁fort , ▁composed ▁of ▁a ▁rect angular ▁def ensive ▁wall , ▁rect angular ▁to wers ▁and ▁a ▁gate ▁in ▁the ▁middle ▁of ▁each ▁of ▁the ▁walls . ▁ ▁The ▁pla cement ▁of ▁the ▁fort ▁was ▁strateg ically ▁deliber ate ▁as ▁it ▁lay ▁not ▁only ▁along ▁the ▁course ▁of ▁the ▁Dan ube ▁River ▁but ▁also ▁at ▁the ▁very ▁mouth ▁of ▁the ▁Black ▁Sea . ▁ ▁Early ▁connections ▁to ▁the ▁Roman ▁fleet ▁and ▁its ▁mar itime ▁activities ▁at ▁Hal my ris ▁are ▁confirmed ▁from ▁ep ig raph ic ▁evidence ▁mention ing ▁the ▁existence ▁of ▁a ▁' mar iner ' s ▁village ' ▁or ▁vic us ▁classic orum ▁. ▁However , ▁a ▁significant ▁alter ation ▁of ▁the ▁def enses ▁took ▁place ▁during ▁the ▁T etr archy ▁period . ▁ ▁The ▁new ▁layout ▁of ▁the ▁fort ▁walls ▁consisted ▁of ▁an ▁irregular ▁polygon ▁bol ster ed ▁by ▁ 1 5 ▁to wers ▁and ▁at ▁least ▁two ▁well - def ended ▁gate ways ▁in ▁the ▁north ▁and ▁the ▁west . ▁Struct ures ▁found ▁within ▁the ▁fort ▁include ▁numerous ▁bar ra cks , ▁a ▁private ▁ther