The Walls of Dubrovnik (Croatian: Dubrovačke gradske zidine) are a series of defensive stone walls that have surrounded and protected the citizens of the afterward proclaimed maritime city-state of Dubrovnik (Ragusa), situated in southern Croatia, since the city’s founding prior to the 7th century as a Byzantium castrum on a rocky island named Laus (Ragusia or Lave). With numerous additions and modifications throughout their history, they have been considered to be amongst the great fortification systems of the Middle Ages, as they were never breached by a hostile army during this time period.[2] In 1979, the old city of Dubrovnik, which includes a substantial portion of the old walls of Dubrovnik, joined the UNESCO list of World Heritage Sites.
The oldest systems of fortifications around the town were likely wooden palisades. Today’s intact city walls, constructed mainly during the 12th–17th centuries, mostly a double line, have long been a source of pride for Dubrovnik. The walls run an uninterrupted course of approximately 1,940 metres (6,360 ft) in length, encircling most of the old city, and reach a maximum height of about 25 metres (82 ft). The bulk of the existing walls and fortifications were constructed during the 14th and 15th centuries but were continually extended and strengthened up until the 17th century.
https://www.godubrovnik.guide/dubrovnikthingstodo/ancient-city-walls/