Castle layout researchers focus on Sugiyama Castle.
Features
Main Enclosure, Center of Castle
The Main Enclosure is the largest and highest one in the castle. It has three entrances in the south, north and east. The north and east ones were also strictly protected by other enclosures and dry moats like you simulated in the south. The lord of the castle would be able examine the situation in all directions clearly and give the appropriate instructions.
In addition, some bypass routes are set in the castle, but some of them are dead-end alleys. If you see the layout of the castle, you may think it looks like a maze. It’s true for enemies, but it’s a well-designed fortress for defenders.
Later History
The ruins of Sugiyama Castle were not known to the public until around 1980s. Only the researchers who studied the layout of castles were interested in this castle. They published the dictionaries and magazines which featured the layout of castles since 1987. The layout drawing of Sugiyama Castle has been one of the most featured ones in these books. The castle became popular little by little. After the excavations between 2002 and 2007, the ruins became a National Historic Site in 2008. It is considered one of the “Hiki Castles Ruins”.
My Impression
I imagine if Sugiyama Castle was much larger, and equipped with turrets, gates, and stone walls, it would look like the great castles built much later, such as Himeji Castle. This means Sugiyama Castle could be the pioneer of the advanced castle design. However, I rather prefer the effort of building the castle to its historical value. The unknown builders of the castle must have had a small budget, resources, workers, and little time because the purpose of the castle was limited. They thought hard to create their great work under the difficult situation. It may have been easier for them to build a great castle if they had enough resources. I think Sugiyama Castle is also a good lesson for us about how to use limited resources to create good work.
How to get There
I recommend using a car when you visit the ruins. It is about 15 minutes away from Ranzan-Ogawa IC on Kanetsu Expressway. The ruins offer a parking lot. By public transportation, take the Tokigawa-cho route bus bound for Seseragi Center from Musashi-Ranzan Station on the Tobu-Tojo Line and get off at the Taguro bus stop. It is about 20 minutes on foot from the bus stop.