How Castles Communicated With Each Other
Satellite System
In Japan Daimyo often relied on more than one castle. The network created by the many daimyo castles is called a satellite system. Daimyo often had one main castle with many satellite castles. Around these satellite castles there may even be sub satellite castles. As more castles were needed more castle were built with the elements of that time period. This allows historians to see many generations of castles all the way up to the 1590's.
How to Find Castles Now:
Today old castle sights are hard to find on modern maps. Castles are typically found in the center of successive rings of defensive walls. Where the walls have disappeared there are usually hills. Below the walls are the Samurais' houses. The temples were placed on the outside as part of a defensive tactic.