Since 16 July 2011, the Pod Blachą Palace has been open to visitors to the restored interiors of the residence of Prince Józef Poniatowski, Polish general, Minister of War and Commander-in-Chief of the Polish Army of the Duchy of Warsaw and Marshal of France. The duke's suite on the first floor of the palace was restored to its former appearance thanks to, among other things, the surviving Inventory of the duke's remains from 1814, and the original layout of the rooms could be reconstructed mainly on the basis of the projections of the palace made by the architect, Wilhelm Henryk Minter, in 1814, after the death of the duke. The source of the interior furnishings became furniture and works of art (among them many donations), collected by the Castle for many years.

The restoration of the King's Nephew Suite, with whose figure the Pod Blachą Palace is primarily associated, not only completes the process of fully restoring the building, but also crowns the many years of restoration work at the Royal Castle in Warsaw.

The ceremonial opening of the exhibition with the participation of the President of the Republic of Poland, Bronisław Komorowski, shortly after Poland assumed the Presidency of the Council of the European Union, testifies to the special contribution of the Castle to cultural activities dedicated to the Polish Presidency of the EU.