Oolong built this mansion with the money he stole from the nearby village. He captured three girls from the village: Sarah, Alexi and Little Flower, but they were freed when Goku captured him. It is never revealed if Oolong came back to his mansion after he left with Goku and Bulma. Oolong also never mentions his mansion for the rest of the series.
Video game appearances
Oolong's mansion is the place where the boss fight against Oolong takes place in Dragon Ball: Shenron no Nazo and Dragon Ball: Origins. In Dragon Ball: Origins, it is a stage where Goku goes through many obstacles, puzzles and open doors by hitting switches. In the bonus level 2-7 in this video game, Bacterian takes over Oolong's mansion and the Sherman Priest asks Goku if he can dislodge him because the animals of the region take refuge from Bacterian's odor to Aru Village.