gatehouse

/G EY1 T HH AW0 S/
noun
  1. 1

    A lodge besides the entrance to an estate; often the residence of a gatekeeper; also a dwelling formerly used as such a residence.

  2. 2

    A fortified room over the entrance to a castle or over the gate in a city wall

  3. 3

    A shelter for a gatekeeper.

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