Japanese castles were originally designed to defend against enemy invaders. With the rise of feudalism in the 16th century, they received their architectural forms and served the feudal lords (daimyô) as military headquarters, residential residence and as a prestige object of their political power. The most important building material for the majority of the old defensive fortifications was wood – as can still be seen today in the original preserved castles. There are three different types of castle constructions: 1. yamajiro = “castle in the mountains”, 2. hirayama-jirô = “castle on a plateau or elevation” and 3. hira-jirô = “castle in the plain”. Most of the rebuilt and reconstructed castle complexes today are made of concrete and have a modern interior – mostly in the form of a museum.