Wu Shangxin made his fortune in Taiwan's salt trade, an industry that concentrated enormous wealth in relatively few hands during the Qing dynasty era. Around 1828, he acquired the garden previously owned by He Bin and transformed it into the Purple Spring Garden, a name that carried connotations of imperial elegance. The garden became known as one of the Four Great Gardens of Taiwan, alongside the Lin Family Mansion and Garden in Wufeng, the Beiguo Garden in Hsinchu, and the Lin Family Mansion and Garden in Banqiao. That ranking placed it among the island's most significant private estates, a reflection of both Wu's wealth and his taste. The family's prosperity generated the proverb that their riches and their property were each independently beyond comparison.

Fortunes turn. During the Japanese colonial period, the Wu family's wealth declined, and the garden was confiscated by Tainan Prefecture. What followed was a gradual dismemberment of the estate. In 1911, the Former Tainan Assembly Hall was built along the garden's southern edge. The Four Seasons Inn went up on the southeastern side. In 1920, the Tainan Library occupied the northwestern corner. In 1922, the Tainan Municipal Swimming Pool was constructed on the northern edge. By 1974, the inn, library, and bathhouse had all been sold to Far East Department Store, which now operates its Park Branch on the site. A garden that had once been a unified private landscape became fragmented among public institutions and commercial enterprises, each taking a bite from the perimeter.

In 1994, a proposal for commercial development on the remaining garden grounds threatened to erase what was left. The plans were dropped, and Wu Garden has been preserved to this day. What survives is a green space in the heart of Tainan's West Central District, a rockery garden with artificial hills modeled after famous Chinese landscape features, ponds, and mature trees that shade paths where salt merchants once strolled. The Former Tainan Assembly Hall, which claimed the garden's southern boundary over a century ago, now functions as a complementary cultural venue. The garden's persistence is not heroic so much as stubborn. It exists because at every moment when it might have vanished, someone decided not to build on it. In a city as dense and commercially active as Tainan, that restraint is its own kind of monument.