The Japan Castle Association’s 100 Famous Castles list includes sites ranging from fully intact castles with original keeps to earthwork ruins. This guide explains how to read castle layouts using key terms (honmaru, kuruwa, horikiri, koguchi), categorizes castles by type (flatland, mountain, hilltop), and compares major castles by region with a focus on surviving structures. A stonework technique table helps readers date construction periods on-site.