Maeda Toshinaga was only 43 when he retired as daimyo of Kaga Domain in 1605, handing the position to his younger brother Toshitsune, who had married the daughter of Shogun Tokugawa Hidetada. The move was strategic: by linking the Maeda bloodline to the shogun's family, Toshinaga secured the clan's future. He withdrew from Kanazawa Castle to Toyama Castle, where he intended to live out his days. But in 1609, Toyama Castle burned. Toshinaga relocated temporarily to Uozu Castle and petitioned the shogunate for permission to build a new residence at a site called Sekino. When the castle was completed, the location was renamed Takaoka, a name the city still carries. The entire project unfolded in the western reaches of old Etchu Province, at the crossroads of the Hokuriku highway and the road to Noto Province, a site that had served as a provincial center since the Muromachi period.

Takaoka Castle stretched 400 meters long and 200 meters wide, a flatland rectangle surrounded by moats. Its five enclosures were arranged with the inner bailey centered along the western edge, flanked by smaller compounds to the north, east, and south. The west side needed no secondary enclosure because a natural marsh already guarded the approach. Takayama Ukon drew inspiration from the Jurakudai, Toyotomi Hideyoshi's lavish palace in Kyoto, prioritizing visual grandeur and ceremonial prestige over military function. The secondary enclosures were poorly suited for defense. Instead, they framed beautiful sightlines along the moat waters. Whether a tenshu keep or yagura watchtowers ever crowned the walls remains unknown. The castle was a retirement residence for a lord who had already fought his last battles, and its architecture reflected that peace.

Toshinaga did not enjoy his new castle for long. After his death, the Maeda clan rebuilt Toyama Castle as the administrative center of Etchu Province and repurposed Takaoka Castle's grounds for more practical use. The enclosures that once hosted a retired lord became storage for tax rice collected across Kaga Domain. Sake breweries, salt warehouses, a gunpowder factory, and the offices of the Takaoka Machi-bugyo, the local governor, filled the castle grounds. For two centuries, the site functioned as a working compound rather than a noble residence. In 1821, fire swept through and destroyed many of these buildings. After the Meiji Restoration ended feudal rule, the government built the district office for Imizu District on the site, completing the castle's transformation from military stronghold to bureaucratic outpost.

What remains of Takaoka Castle is mostly stone ramparts tracing the old enclosure lines and the moats that Ukon designed for their beauty. The ruins became a public park in 1875 and were elevated to a Toyama Prefectural park in 1967. Today the grounds hold the Imizu Jinja, a Shinto shrine ranked as the ichinomiya, the first shrine of Etchu Province, along with the Takaoka Municipal Museum, Takaoka Public Hall, and a small zoo. But the park's defining feature arrives each spring, when hundreds of cherry trees burst into bloom along the moat edges, making Takaoka Castle Park the city's premier hanami destination. The site is a ten-minute walk from Takaoka Station on JR West's Hokuriku Main Line, or five minutes from Etchu-Nakagawa Station on the Himi Line. The castle ruins are designated a National Historic Site, a quiet recognition that what matters here was never the warfare, but the water and the trees.