Azuchi Castle was Japanese warlord Oda Nobunaga's great citadel at Azuchi on the shores of Lake Biwa in central Japan. Constructed at massive expense from 1576 to 1579, the fortress revolutionized Japanese castle building, and set the pattern for all future Japanese castles, including Osaka, Edo, and Himeji Castles.
Positioned at the top of a towering precipice jutting up sharply out of a flat plain at the edge of Japan's largest lake, the castle not only gave its defenders impressive views in all 360 degrees, but perhaps almost importantly, allowed the castle to be seen from all directions as well. Moreover, its strategic location at the very center of Japan allowed Nobunaga to command the gateway to the Imperial capital at Kyoto as well as protecting western Japan (which was under his firm control) from his powerful enemies in the East, the mighty Takeda and Uesugi clans.
What Nobunaga recognized in building Azuchi Castle, was that a castle could not only serve a military denfense function, but could also become a symbol of the ruler's wealth and power, inspiring awe and fear in his subjects. Indeed, whereas previous fortresses in Japan had been simple, even austere affairs, whose design focused entirely on functional military aspects, Azuchi Castle was at least as much a palace as it was a fortress, lavishly decorated on its exterior with elaborate carvings and gold leaf, and sumptuously apppointed on the interior with expensive furniture and objects of art.
Among the other innovations in Azuchi Castle which would later be copied by future warlords were the unusually large and prominent donjon (at seven stories tall, one of the largest ever built), the massive, mortar-less stone outer walls, and the irregularly-shaped outer defense works, with numerous dead ends and blind alleys to confuse attackers.
Azuchi Castle was also the center of the first true "castle town," because in addition to the citadel Nobunaga also had a whole town built around the castle, and ordered all of his followers to move there. This castle town model would soon be appropriated by all the other warlords in Japan.
Unfortunately, for all of its beauty and impressive scale, Azuchi castle did not last very long. Just three years after it was completed, in 1582, Nobunaga was assassinated by one of his generals, Akechi Mitsuhide, who then besieged Nobunaga's followers at Azuchi and razed the castle to the ground. Today, only the massive stone walls and foundation remain.