In Team Fortress Classic, an area, usually of significant strategic importance, that is guarded by (generally two or more) sentry gun(s). Classic examples include flag rooms, capture points in invasion maps such as Avanti or Dustbowl, capture points in territorial control maps such as Canal Zone 2, and ramp rooms.

Sentry gun nest removal is often difficult and, as a rule, deadly. As each nest is different, there are no hard and fast rules, although there are general guidelines that may be of use: