At

Syntax: at <location> <command>

AT executes the given command (which may have arguments) at the given
location. The location may be specified as a vnum, as the name of
a mobile, or as the name of an object.

AT works by temporarily moving you to that location, executing the
command, and then moving you back (if the command didn't change your
location). Thus, AT will not work to private locations.