His father, Miksa Neumann (1837–1912), was the vice-president of the Budapest Commodity and Stock Exchange and was a member of the Chevra Kadisa in Pest for decades, and his mother was Júlia Heiduschka.
[5] He later studied at the Königliche Bauakademie in Berlin, and eventually made his way to Munich, where he received his degree in architecture as a student of the famous German Baroque-revival architect Friedrich von Thiersch.
During this time their main commissions consisted of Baroque-revival tenements and apartment houses, which were quickly becoming some of the most popular residential type in Budapest.
[7] Kőrössy split from Sebestyén in 1899 and built his own house at Városligeti fasor 47 in Budapest, which was heavily influenced by Belgian, French and German Art Nouveau/Jugendstil.
In 1909 he formed a partnership with Geza Kiss, and together they completed three major buildings for financial institutions, most significantly the Palace of the Hungarian Agricultural and Means Bank Limited Liability Company on Nador utca (1912).
[9][10] With Michailich Győző, he also designed the Decebal Bridge, a reinforced concrete structure over the Bega River in Temesvár (now Timișoara, Romania) in 1908, which at the time was the longest of its type in the world.