Nagoya Castle is known for its unique "connected-keep" style of construction, with the main keep of five stories on five different levels and a smaller keep of two levels joined by an abutment bridge. Evidence that another small keep was planned for the west side of the main keep can be found in traces of an entryway in the upper part of the stone wall foundation on that side. The entryway to the small keep was also planned for the west side. However, during the construction, the location was changed to where it is today. Traces of the original entryway remain inside the stone wall.