Finally, in the fall of the same year, she transferred to the Technische Universität Darmstadt (Technical University in Darmstadt), where she successfully enrolled as a regular student in the mechanical engineering program. A year later, she switched to structural engineering/architecture and passed the Diplom-Hauptprüfung (main diploma examination) in December 1922.

After graduating, she worked in residential construction in Darmstadt and Berlin and was able to contribute to villa buildings under the influence of Mendelsohn and Gropius. From 1926 to 1928 she lived in Moscow and was active in building cooperatives in the construction of workmen’s homes.

After her return from Russia, on 25 November 1928, she took part at the founding congress of the Bundes der Freunde der Sowjetunion (League of Friends of the Soviet Union) in the ballroom of the Association of Engineers and Architects in Vienna. She spoke about the building activities in the new Russia and wrote several articles on the subject, which were published in renowned journals. For example, in the journal edited by Ernst May: Das neue Frankfurt as well as in the journal of the Deutscher Werkbund Die Form. As a writing architect, she reported on the Soviet building scene and critically dealt with the emerging contradictions in Soviet society.

She participated in two CIAM congresses in the following years:

1929 at CIAM II in Frankfurt am Main: ‘Die Wohnung für das Existenzminimum’ (‘Housing for the Subsistence Minimum)’ and 1930 at CIAM III in Brussels: ‘Rationelle Bebauungsweisen’ (‘Rational Construction Methods’).

During a longer stay abroad, in 1930 in Arosa, Switzerland, she had the opportunity to work on various building projects (villas, sanatoriums and hotel kitchens). Here it was above all the influence of the Dutch architect J. J. P. Oud, whom she particularly admired, that helped her to form her modern style. This was characterised by unpretentious simplicity as well as practicality.

Her most famous traces in Vienna are to be found in the Vienna Werkbundsiedlung, where this reduced style and her design, characterized by clear forms, can be found in the furnishings of Hugo Häring’s house number 1.

As a Jew and convinced Social Democrat, Leonie Pilewski fled from Vienna via Switzerland to Sweden on 12 March 1938 to escape the Gestapo and settled in Stockholm. In 1940 she married the Swede Olof Karlsson. As far as is known, she was in poor health and devoted herself to painting in the following years. Under the name Leonie Pilewski-Karlsson she participated in several exhibitions. Her art shows still life, flowers and landscapes in oil, pastel, gouache, or watercolour.