who was one of the founding fathers of 20th‐century pure mathematics and in many ways the originator of the formalist school of mathematics which has been dominant ever since. Born at Königsberg (Kaliningrad), he became professor at Göttingen in 1895, where he remained for the rest of his life. One of his fundamental contributions to formalism was his Grundlagen der Geometrie (Foundations of Geometry), published in 1899, which served to put geometry on a proper axiomatic basis, unlike the rather more intuitive ‘axiomatization’ of Euclid. He made major contributions to mathematical analysis and many other areas. At the International Congress of Mathematics in 1900, he opened the new century by posing his famous list of 23 problems, which have since influenced much research in mathematics.

http://aleph0.clarku.edu/~djoyce/hilbert/ The 23 mathematical problems of Hilbert.