Orco said the transaction included loan receivables acquired from Poland's bank Pekao.
The Zlota 44 building, designed by modernist architect Daniel Libeskind, is one of the most prominent constructions in the Polish capital and stands near the Palace of Culture and Science, Warsaw's tallest building.
Orco, whose largest shareholder is Czech investor Radovan Vitek, had suffered deep losses through the global financial crisis.
The stock has dropped to less than 1 percent from its 2007 highs and the company will delist form the Prague Stock Exchange on Sept 22, while remaining listed in Paris and Warsaw.