After passing through the Naka-no-mon Gate and turning left, you come to a gentle slope. Going up this slope, you reach an area covered with bushes; this is the former site of the Shin-mon (Shin-go-mon) Gate. Turning right from there, you will see an impressive stone wall built tightly with massive stones. This is the masugata (gate square) of the Chujaku-mon Gate (Goshoin Gate).
 Immediately to the right of the Shin-mon Gate site once stood an outer gate. On top of the stone wall to the left when facing this gate, there were formerly two double-story turrets, known as the Shoin-de Turret (Jubako Turret) at the front and the Shoin Double Turret behind it.

 Today, there are no buildings remaining at the location where the outer gate of the Chujaku-mon Gate once stood, and the ground has been neatly paved. Unless you are told that a gate once existed here, you would not notice it. However, if you look closely at the stone wall, you can see small holes. These may be traces left by a former structure.

 It is believed that some of the stones used in the stone walls of this gate were repurposed from the stones of the Tenshudai (main keep foundation), which were burned in the Great Fire of Meireki in 1657. Turning right inside the masugata, there once stood an inner gate. Looking at the ground, you can still see foundation stones with round holes, allowing you to imagine that a gate once stood here.
 If you examine the nearby stone walls, you will notice that the stones are darker in color, more rounded, and that the surface of the wall is uneven. In contrast, the stone walls of this gate as a whole are carefully fitted with no gaps and have a beautifully flat surface. Why is only this section uneven? It is thought that a major fire occurred in 1863, destroying the inner gate. If so, the foundation stones of this gate may have been burned twice by large fires.
 Passing through this inner gate leads to the former Honmaru (main enclosure) of Edo Castle. None of the palace buildings remain today, and beyond the wide grassy lawn, the Tenshudai can be seen in the distance.