400 (disambiguation)
# 400 (disambiguation)

400 may refer to:

* 400 (number), the natural number following 399 and preceding 401
* A year: 400 BC or AD 400
* The Four Hundred, the oligarchic government controlling Athens after the Athenian coup of 411 BC
* The Four Hundred (1892), the social elite of New York City in the late 19th century
* The Four Hundred (band), an American indie rock band
* The Game's Four Hundred, the subtitle of the almanac, the Baseball Register
* List of highways numbered 400
* Twin Cities 400, a passenger train operated by Chicago & Northwestern Railway from 1935 to 1963
* 400 (card game), a Lebanese trick-taking game
* HTTP 400, the HTTP error code for "Bad Request"
* Ping Shan stop, Hong Kong; station code
