FBI house

An FBI house is a normal-looking residential house that is owned and occupied by
FBI agents, usually two of them who are partners, and which is used to spy upon a
targetted individual on a long-term basis.
FBI houses can often be recognized by their bright external lights on the
front of the house, which are on all night.
Such lights serve to give a better image to their cameras,
which are used to watch the targetted person leave or return to their house.
Oftentimes there are two or more of such houses in the vicinity of a targetted person's house,
so as to get more-thorough views thereof.
Sometimes the FBI will dip into their budget and build a two-story house,
so as to better see into a targetted person's backyard.
Your tax-dollars at work.

Watching the person leaving and returning is the most basic function of such houses,
but hardly the only one.
Knowing when a targetted person is away from their house is essential for
knowing when to execute secret "sneak-and-peak" warrants.
Such houses can also serve as locations of "tempest" equipment which can see
the content of computer-screens, television-screens, and smartphone-screens through walls,
via radio-frequency emissions therefrom.
-And that is not the only spy-technology that the FBI can use
while using such a house as a base.