Hübner-Haus, Commercial building in Neustadt district, Hamburg, Germany.

Hübner-Haus is a five-storey corner office building at Poststraße 2–4 and Bei der Stadtwassermühle, joined to the older house at Neuer Wall 22. Henry Grell designed the 1909 extension, whose closely spaced columns and flat bay windows follow the office architecture of the period. Its entrance hall is decorated in the style of the Wiener Werkstätte, with marble walls and coloured mosaic tiles on the inner door frames.

Georg Hübner junior bought the plots at Poststraße 2–4 and Bei der Stadtwassermühle in 1907, adjoining his existing premises at Neuer Wall 22/22a. Architect Henry Grell designed the five-storey corner building, largely of concrete, completed in 1909 and regarded as Hamburg's first concrete building. It is listed as a monument at Bei der Stadtwassermühle 1 and Poststraße 2–4.

The café and pastry shop run by Mathilde Hübner occupied the two lower floors of the corner building from 1909. It was exclusive enough that women could meet there for coffee, tea or hot chocolate without a male companion, unusual in Hamburg at the time. Drawings in a stairwell showcase show well-dressed women in large hats and gentlemen of Hamburg society who were regular guests.

The building stands at the corner of Poststraße and Neuer Wall, with a second frontage on Bei der Stadtwassermühle. Shops occupy the ground floor and mezzanine; offices and doctors' practices fill the floors above, and the Hübner Grundstücksverwaltung has its office on the top floor. In the ground-floor entrance, look for the Hübner-Haus inscription above the door, the double-H door handles, the marble walls and the coloured mosaic tiles on the intermediate door frames.

During World War II, the building played a lifesaving role because its working water pump supplied the nearby population during shortages. This practical function made it a crucial resource for neighbors surviving the difficult war years.