  We construct special solutions of the Nambu-Goto equations for stationary
strings in a general Kerr-NUT-(A)dS spacetime in any number of dimensions. This
construction is based on the existence of explicit and hidden symmetries
generated by the principal tensor which exists for these metrics. The
characteristic property of these string configurations, which we call
"principal Killing strings," is that they are stretched out from "infinity" to
the horizon of the Kerr-NUT-(A)dS black hole and remain regular at the latter.
We also demonstrate that principal Killing strings extract angular momentum
from higher-dimensional rotating black holes and interpret this as the action
of an asymptotic torque.
