It was decorated with pediment reliefs showing the triumph of the legendary "ancestor" of the Ślepowron and Korwin Polish clans, the Roman commander Manius Valerius Maximus Corvinus Messalla (263 BC) and sculptural work, all by Andreas Schlüter.

[4] Jan Dobrogost Krasiński, who also served as the royal clerk (Referendarz), was a descendant of old Mazovian nobility and an heir to a large fortune.

After his father's death he wished to erect a magnificent residence in the capital which was to fulfill his excessive political ambitions and show his enormous pride, which made him cultivate and develop a 16th-century legend about the antique origin and alleged royal connections of his family.

The first floor porte-fenêtre (vertical French door and window) was crowned with a cartouche supported by two angels bearing the founder's monogram JK for Jan Krasiński.

[5] The palace-garden complex was created on a vast property between Długa and Świętojerska Streets, in the place of the old manor house with small garden that belonged to Krasiński.

It houses a large permanent exhibition consisting of some of the priceless objects from the National Library including Sankt Florian Psalter, Holy Cross Sermons, manuscripts of the chronicles of Gallus Anonymus and Wincenty Kadłubek, Medieval and Renaissance works of European thinkers as well as works by Jan Kochanowski, Adam Mickiewicz, Juliusz Słowacki, Frédéric Chopin, Henryk Sienkiewicz, Zbigniew Herbert, Henryk Górecki and Agnieszka Osiecka.