The Nostrade's Mansion is a house owned by the Nostrade Family, Light Nostrade and his daughter Neon Nostrade. Being a high-profile individual within the Mafia Community, Light is able to afford such a luxurious mansion.
Yorknew City arc
After being appointed by the Sengi Guild's agent, Kurapika proceeds to the Nostrade Mansion where he has an interview as a possible bodyguard, along with five other applicants. He waits outside the gates until a butler allows him to enter.
Greed Island arc
Killua contacts Kurapika in order to inform him that the Phantom Troupe may get an Nen exorcist to remove the Judgment Chain around Chrollo's heart, to which Kurapika was already aware of the possibility. He is then informed by his co-worker Melody that their boss has summoned him. Kurapika sees his sloven boss in his messy room and beseeches him what to do for that month. As reassuring as Kurapika was to have him take care of everything, his boss still chastises him and demands that his daughter have her powers returned to her.