Before there was a castle, there was a council. Iga Province occupied a mountain-ringed basin on the route connecting Nara and Kyoto with the Ise Grand Shrine and the eastern provinces. Isolated by geography, the local warrior families -- jizamurai -- maintained their independence through asymmetric warfare tactics that later became known as ninjutsu. From around the 1460s, when the Ashikaga shogunate's authority crumbled, these clans formalized their self-governance as the Iga ikki, a league of all the commons of Iga. Their headquarters sat on the hilltop where the castle now stands. This arrangement persisted until 1581, when Oda Nobunaga, Japan's great unifier, launched a massive multi-directional invasion after his son's first attempt had been humiliated by the ninja's unconventional tactics. The ninja republic fell, but the place remembered what it had been.

Construction began in 1585 under Takigawa Katsutoshi, but the castle took its real shape under two successive lords. Tsutsui Sadatsugu, transferred from Koriyama Castle in Yamato Province under Toyotomi Hideyoshi, divided the hilltop into upper and lower sections and built a three-story tenshu on the eastern edge. After the Battle of Sekigahara in 1600, Tokugawa Ieyasu expelled the pro-Toyotomi Tsutsui and installed Todo Takatora -- a general with a remarkable second career as one of the Sengoku period's finest castle architects, credited with designing or rebuilding at least twenty castles including Uwajima and Imabari. Todo Takatora gave Iga Ueno its defining feature: the towering honmaru walls, roughly 30 meters high, that remain the tallest castle stone walls in Japan. He expanded the grounds to 800 by 400 meters and began a new five-story tenshu. Then in 1612, a windstorm destroyed the tower before it was completed. After the Toyotomi clan fell at the Siege of Osaka in 1615, there was no longer any reason to rebuild it.

The Meiji restoration swept away what remained of the castle's original structures. For decades, the hilltop held only its enormous stone walls and memories. Then in 1935, a wooden reconstruction of the tenshu rose above the honmaru, giving the castle its current silhouette -- a graceful white tower that earned the nickname Hakuho-jo, White Phoenix Castle. The reconstructed keep houses a museum of local history. In 2006, the Japan Castle Foundation named Iga Ueno one of Japan's Top 100 Castles. The site also attracted the eye of Akira Kurosawa, who filmed battle scenes for his 1980 epic Kagemusha against the backdrop of those legendary stone walls. The highest fortifications in the country provided the perfect stage for a film about a warlord's imposing shadow -- a fitting choice for walls that have always been more impressive than anything they contained.

Iga Ueno Castle is preserved as Ueno Park, and the hilltop has become the cultural anchor of the city of Iga. Immediately alongside the castle stands the Iga-ryu Ninja Museum, drawing the threads of the site's layered history together: ninja governance, samurai conquest, and modern tourism side by side on the same ground. The castle is a thirty-minute walk from Iga-Ueno Station on the JR West Kansai Main Line or five minutes from Uenoshi Station on the Iga Railway. Visitors who climb the stone steps to the honmaru and look out from the base of those 30-meter walls see the same view the ninja ikki once surveyed -- a basin enclosed by mountains on all sides, the rivers threading through the valley floor, and the routes to Nara, Kyoto, and Ise radiating outward like spokes from a place that has always sat at the crossroads.