Prince Jozef Poniatowski (1763 - 1813) was a nephew of the last king of Poland, Polish general, minister of war and army chief.
In 1813 he was nominated by Napoleon the Marshal of France, which was the only such distinction for a foreigner in France's history.
http://en.wikipedia.org/wiki/J%C3%B3zef_Antoni_Poniatowski
The bronze statue for the monument was made in 1832 by Danish sculptor Bertel Thorwaldsen (the same who made a Copernicus sculpture).
It is the equestrian statue, portraying the Prince as classical hero in Roman tunic and armor, modelled after the statue of Marcus Aurelius in Rome.
In 1834, the Tsar of Russia forbid to place it in Warsaw and ordered its transfer to Modlin Fortress.
He then gave it to General Ivan Paskiewicz who installed it in his mansion in Homel.
The monument returned to Poland in 1922 and was finaly erected, but was completely destroyed during the WW II.
New mould, made by the model of the old one, was a gift from the inhabitants of Kopenhaag to Warsaw.

The Presidential Palace at Krakowskie Przedmieście Street was built between 1643 and 1645 for Hetman Koniecpolski, the commander-in-chief of the Polish Army.
From the end of the 17th century until 1817, it was the property of the Radziwill family. Several times extended.
Its current Neo-Classical form is a result of remodeling after its purchase by the Polish Kingdom authorities.
The Warsaw Treaty was signed in 1955 in the Palace, and in 1970, the treaty of the normalization of relations between Germany and Poland.
In 1989, it witnessed the Government-Solidarity "Round Table" Talks. From 1994 it is the residence of the President of Poland.