This complex of territories called for a high number of border defences and fortified dwellings, as well as many seats of governance and power. Castles were the popular solution to these requirements, so this proliferation of borders and independent regions would call for a large number of castles.

Germany is home to an estimated 20,000 to 25,000 castles, the highest density in the world, largely due to its fragmented political history. During the Middle Ages, the region was not a unified nation but a patchwork of hundreds of tiny sovereign states, duchies, and principalities within the Holy Roman Empire. Every local lord, count, or knight built a castle to demonstrate their power, protect their territory, and serve as an administrative and tax-collection center. Because these territories were so small and often at odds, castles were built roughly 15 miles apart—the distance an army or an administrator could travel in a single day. These structures evolved from functional wooden forts into massive stone fortresses like the Wartburg and eventually into opulent "fairytale" palaces like Neuschwanstein, built by King Ludwig II as a romanticized tribute to the past. This history of "Kleinstaaterei" (small-state policy) left a permanent architectural legacy that defines the German landscape today, with ruins and well-preserved estates found on nearly every strategic hilltop.