Japan has dozens of samurai-era castles, but the most elaborate is in the city of Himeji. Also known as the “White Heron Castle” because of its distinctive white plaster, the 17th-century fortress reopened in 2015 after a nearly $24 billion renovation. The World Heritage site, west of Osaka last year hosted almost 3 million visitors - a tenth of them from overseas. This old castle lately has received a high-tech makeover. The technology of “augmented reality” helps visitors navigate Himeji’s turrets, towers, gates and other defensive structures via augmented reality guideposts and reenactments.