the arch of the ancient fortress of cape kaliakra above the sea against the background of the azure sky. northern black sea coast,

already ancient antique arch architecture azure background bay beautiful beauty become black blue building bulgaria cape castle cave city cliff coast color colored colors culture europe fortress heritage historic historical history huge island kaliakra landmark landscape medieval monument mountain natural nature northern ocean old one only outdoor part restored rock ruin sand scenic sea see sky stone sun that tourism tower town travel vacation view wall water wave when