Conversation so far:
What can you tell me about  Atlantic City casinos?
In 1976, New Jersey voters legalized casino gambling in Atlantic City. The first casino opened two years later.
Was Donald Trump in New Jersey when casino gambling was legalized?
why did Donald Trump decide to go to Atlantic City?
In 1984, Donald Trump opened Harrah's at Trump Plaza hotel and casino in Atlantic City, New Jersey with financing from the Holiday Corporation, who also managed the operation.
what did Donald Trump do once get to to Atlantic City ?
In 1984, Donald Trump opened Harrah's at Trump Plaza hotel and casino in Atlantic City, New Jersey with financing from the Holiday Corporation, who also managed the operation.
What was special about the Harrah's at Trump plaza?
Harrah's at Trump Plaza contained 614 rooms, seven restaurants, a health club, a 750-seat showroom and a 60,000 sq.ft. casino, all on a narrow 2.6-acre plot of land.
was Harrah's at Trump plaza sucessful?
Harrah's at Trump Plaza's poor financial results worsened tensions between the Holiday Corporation, and Donald Trump.
tensions between the Holiday Corporation and Donald Trump led to what?
Donald Trump paid the Holiday Corporation $70 million in May 1986 to take sole control of Harrah's at Trump Plaza.
What else did Donald Trump own in Atlantic City besides Harrah's at Trump Plaza?
Donald Trump had also acquired a partially completed building in Atlantic City from the Hilton Corporation for $320 million, naming it Trump Castle upon completion.

Question: for how much did he get the building?
Self-contained rewrite: for how much did Donald Trump  get the partially completed Building in Atlantic City acquired from the Hilton corporation?