Located in the Setagaya neighborhood, this park marks the ruins of what was once the Setagaya Castle. According to history, the castle once belonged to the Kira clan in the 14th century until its abandonment. Well-maintained enclosures, earthworks and dried moats remain in the park today. This spot is just a walking distance away from Gotokuji temple (one of the mansions which belonged to the Kira clan), where the grave site of the daimyo (feudal lord) Ii Naosuke is located. The temple makes for a great side trip when in the area.