Halle 400, Event venue in Gaarden East, Kiel, Germany.

Halle 400 is a former industrial hall on the eastern shore of the Hörn in Kiel, now used as an event venue and office building. It has two halls and four main rooms that can be combined or used separately, plus a restaurant with a beer garden. The building is a reinforced concrete skeleton structure, the first of its kind in Kiel, and retains a loading crane from its shipyard past.

The hall was completed in early 1939 as a reinforced-concrete skeleton building, the first of its kind in Kiel, on the Germaniawerft shipyard site. It served as a copper smithy and tin foundry and as workshops for ship engines and compressors. After the war, Howaldtswerke-Deutsche Werft used it for submarine construction until 1989. The city of Kiel bought it in 1991, and from 1995 to 1998 the Kiel Schauspielhaus performed in its basement.

The street where the hall stands is named Halle400 after the building itself. Until 2020 the four main rooms could be booked separately with their own entrances or combined into one large hall; the modular layout hosted weddings, anniversaries and gala events alongside concerts by Wir sind Helden, Schandmaul and comedians Dave Davis and Jürgen Becker. Since autumn 2020 the building has housed a Kindertagesstätte, a daycare centre.

The building stands on the Kieler Ostufer at the Hörn, in the Kai-City Kiel, a few minutes' walk from the city centre; the street it faces is itself named Halle400. Since autumn 2020 it has operated as a Kindertagesstätte, so the halls are no longer open to event visitors. The former outdoor area was the second-largest in Kiel, and a HDW loading crane was kept during the 2002 renovation.

A loading crane from Howaldtswerke-Deutsche Werft survived the 2002 renovation and stands in the building as a reminder of its shipyard past. The hall itself was built in early 1939 as Kiel's first reinforced-concrete skeleton structure, and an air-raid shelter for nearly 1,500 people was attached to it.