Myouryuji (Ninja Temple), Kanazawa.

“Myōryū-ji, commonly known as Ninja-dera, is a Buddhist temple belonging to Nichiren sect located in the city of Kanazawa, Ishikawa, Japan. While not actually associated with ninjas, the temple earned its nickname because of its many deceptive defences.”

You can’t take photos inside, but I recommend doing the guided tour.