How do natural barriers impact location choices for castles in medieval times?

Natural barriers significantly influenced the strategic decisions made when choosing locations for castles in medieval times, primarily because these barriers offered critical protection against enemies. Examples of such natural obstacles include mountains, rivers, and dense forests, which could deter an advancing army or slow down their approach. By situating a castle near or within these barriers, defenders could take advantage of the landscape to create a fortified position that was harder to breach.

While some of the other options touch on relevant aspects of castle construction and location, none address the primary reason for their placement as effectively as the concept of protection. For instance, while easier construction might seem beneficial, the focus on defense was paramount in castle design. Similarly, enhancing accessibility for trade and ensuring proximity to water sources were important but secondary to the castle's function as a military stronghold. The primary motive for the location of castles was to establish a secure environment from which to defend territory and withstand sieges, which natural barriers facilitated effectively.