Three Warsaw foundation libraries together with their collections, of invaluable rank for Polish culture, ceased to exist during the last phase of the Warsaw Uprising and immediately after its end, in September and October 1944. During the nineteenth century and at the beginning of the twentieth century the three estate residences of the Krasinski, Przezdziecki and Zamoyski families possessed the character of private foundation seats, museum-libraries supervised by their owners - representatives of prominent aristocratic families as well as specially employed custodians and librarians. All three played an extremely essential role during the partition era, and in the inter-war period developed into significant scientific-cultural institutions. During the inter-war period the oldest - the Zamoyski Estate Library, founded by Count Stanislaw Kostka Zamoyski and located in the Blue Palace in Senatorska Street, amassed 70 000 works in 97 000 volumes, more than 2 000 manuscripts, 624 parchment diplomas, over 10 000 autographs, a collection of illustrations and coins, and 315 maps and atlases. Another Warsaw-based library-museum collection belonged to the Przezdziecki family, whose palace in Foksal Street housed a valuable and important book collection totalling 60 000 volumes and 500 manuscripts, an extensive archive containing, i. a. 800 parchment and paper documents, as well as a copious cartographic collection of 350 maps, atlases and plans. The art collection consisted of 10 000 exhibits and examples of the decorative arts. At the beginning of the last century the Krasinski Estate Library and Museum, initially housed in the palace of General Wincenty Krasinski in 5 Krakowskie Przedmiescie Street, was, thanks to the courage and visionary approach of the last heir, Edward Krasinski, transferred to a specially erected library-museum building in 9 Okolnik Street. In 1927 the collection totalled 77 000 works in more than 200 000 volumes, 700 diplomas, 7 000 manuscripts, about 8 000 drawings and illustrations as well as 2 500 maps and atlases. The estate museum boasted of about 900 objects featured in an impressive armoury, a gallery with about 350 canvases by foreign and Polish painters. An end to the existence of all three, magnificently developing scientific-cultural foundation institutions was put by the second world war - remnants of those collections which survived the fires of September 1939 were bombed and burnt in the Warsaw Uprising. Today, not a single foundation exists in its original shape, and although after the war the buildings were reconstructed, they are bereft of the treasures of national culture which they once sheltered. The example of the Libraries and the associated art collections of the Krasinski, Przezdziecki and Zamoyski family estates in Warsaw may serve as an illustration of the potential which up to WW II was displayed by Polish private collections, gathered in cultural and scientific centres derived from, and active under the slogan of 'Amor Patrie nostra Lex'.