Jan Gratama (b. Groningen, 1877) studied Architecture at the Polytechnic School in Delft. After various jobs as a draftsman and teacher in The Hague and Delft, he settled as an architect in Amsterdam in 1908. The first years, however, he would draw attention not so much as an architect but as a profiled administrator and polemical publicist. He was secretary of the Maatschappij tot Bevordering van de Bouwkunst, president of the society Architectura et Amicitia and publicist in the Bouwkundig Weekblad. From 1914 he worked with the architect G. Versteeg, and from 1930 he would collaborate with J.W. Dinger. Gratama sought ways to incorporate modern techniques and modern views on architecture into the existing Dutch traditions and the existing built environment. For example, Gratama was a pioneer in the use of concrete and gained fame with, among other things, a concrete warehouse in the P. Jacobszstraat in Amsterdam. Together with Berlage, he designed a housing complex in the Transvaal neighborhood and would himself design housing complexes in Amsterdam-Noord and the Watergraafsmeer. Together with Dinger, he was also responsible for a number of branches of the Incassobank. In the early years, he sided with the modernists and sought affiliation with the Amsterdam School. Over the years, Gratama moved in a more traditional and historicizing direction. The office building De Bisschop, which he designed in 1934 on the corner of Dam Square and Rokin, marks Gratama's turnaround and became the cause of a sharp polemic between supporters and opponents of modern building. Politically, too, Gratama would continue to advance. During the occupation, he became an alderman in Amsterdam, which led to political difficulties after the war. Gratama died in 1947. The firm was continued by Jan Willem Dinger (Lunteren, 1891) who was less profiled than his companion. Among other things, Dinger would work with I. Blomhert on the Antoni van Leeuwenhoek Hospital on Sarphatistraat in Amsterdam. In addition, Dinger realized a number of housing complexes in Arnhem. Finally, it is notable that over the years Dinger always received a large number of commissions from his native Lunteren, so that many of Dinger's projects were also realized there. J.W. Dinger would pass away in 1986.