blockhouse

/B L AA1 K HH AW0 S/
noun
  1. 1

    A sturdy military fortification, often of concrete, with gunports.

  2. 2

    A reinforced building from which to control hazardous operations, such as an explosion or a rocket launch.

  3. 3

    A temporary wooden fortification with a projecting upper story.

Source: https://en.wiktionary.org/wiki/blockhouse