Wales is often called the "Castle Capital of the World," home to over 600 fortresses, primarily because of its turbulent medieval history and its location on the "frontier" of English expansion. Most of the famous stone castles were built during the late 13th century by King Edward I of England as part of his "Iron Ring" strategy to surround and subdue the rebellious Welsh princes. These massive structures, like Conwy, Caernarfon, and Harlech, were both military strongholds and symbols of English dominance. Additionally, native Welsh princes built their own smaller, rugged castles to defend their territory. The geography of Wales—with its jagged coastline and mountainous interior—made these fortifications essential for controlling trade routes and mountain passes. By 2026, many of these castles have been designated UNESCO World Heritage sites, serving as a permanent stone record of the centuries-long struggle for Welsh independence and the strategic importance of this rugged corner of the British Isles.