Hochhaus Neue Donau also known as the Seidler Tower is a mixed-use high-rise building in the Donau City district of Vienna, Austria. Built between 1999 and 2001, the tower stands at 120 m (390 ft) tall (150 m (490 ft) by antenna spire) with 34 floors and is the current 11th tallest building in Austria.

The elongated triangular design of the 32-story tower is inspired by the goal of maximizing beautiful water views for every apartment. The longer wing is oriented southward toward the Danube, while the shorter wing points east, towards the Kaiserwasser and the Alte Donau.

The building, designed by the Austrian-Australian architect Harry Seidler, was constructed between 1999 and 2001 and has a total of 32 residential floors and one service floor, reaching a height of 120 metres (150 metres with the concrete sculpture on top). The ground floor to the 8th floor mainly contains rental offices. Floors 8 to 15 are divided into two-to three-room apartments, above that there are one-to two-room apartments, and on the top floor there are penthouses. Two basement floors contain garages with a total of 220 parking spaces beneath the plaza.

The vertical core comprises elevators and utilities. It links the two wings with the tower’s additional 7-storey wing, designated for office use. The white aluminum cassette facade is segmented into four sections. These create a triangular center, which is surrounded by three wings. On the ground level, there's the porter's office, which is constantly staffed.

• 
  Neue Donau high-rise, view from the Kaisermühlen subway station
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  View from the southwest
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  View from the southwest with reflection in the New Danube
• 
  View from the Reichsbrücke

• List of tallest buildings in Austria

• Hochhaus Neue Donau: Jüngstes Beispiel für Wiens Sozial-Wohnbau City Hall correspondence of 20 May 2002 (accessed on 29 May 2010)
• Hochhaus Neue Donau at CTBUH
• Hochhaus Neue Donau at Skyscraperpage
• Hochhaus Neue Donau at Structurae
• Hochhaus Neue Donau at SKYDB