The Iga Ueno Castle in Mie Prefecture is also called the Hakuho (“white phoenix”) castle because of its beautiful exterior. It is said that in order to the improve the castle, ninjas from Iga were sent all across the country to study other castles for reference. The stone walls in the inner moat are among the highest in Japan at about 30m. The castle has also been a popular location in Japan for film shooting, given its impressive appearance.