Blame it partly on Wales' history as a contested territory. Fighting over turf, the Normans, the native Welsh, and the English, led by expansionist Edward I, all erected epic fortresses in an explosion of castle building that dominated the 13th and 14th centuries.

Wales is often cited as the "castle capital of the world," boasting over 600 fortresses across its landscape. The primary reason for this high density is the roughly 350 years of intense conflict between the Welsh and the English, particularly during the 13th-century reign of King Edward I. Following his conquest of Wales, Edward I constructed a "Ring of Iron"—a series of massive, state-of-the-art stone castles like Conwy, Caernarfon, and Beaumaris—to pacify and control the Welsh population. Additionally, many smaller castles were built by Marcher Lords (Anglo-Norman nobles) along the border to defend their newly seized lands. Because Wales has a lower population density than England, many of these ruins were never "cannibalized" for modern building materials, allowing them to survive into 2026 as historic landmarks. The sheer number of fortifications reflects a long history of resistance, where the rugged Welsh terrain necessitated permanent military outposts to maintain political and territorial control.