The aftercastle^{[pronunciation?]} (or sterncastle, sometimes aftcastle) is the stern structure behind the mizzenmast and above the transom on large sailing ships, such as carracks, caravels, galleons and galleasses.^[1] It usually houses the captain's cabin and perhaps additional cabins and is crowned by the poop deck, which on men-of-war provided a heightened platform from which to fire upon other ships; it was also a place of defence in the event of boarding. More common, but much smaller, is the forecastle.

This article relies largely or entirely on a single source. (November 2018)

As sailing ships evolved, the aftercastle gave way to the quarterdeck, whose span ran all the way to the main mast.