  We study the structure of stationary and axisymmetric metrics solving the
vacuum Einstein equations of General Relativity in four and higher dimensions,
building on recent work in hep-th/0408141. We write the Einstein equations in a
new form that naturally identifies the sources for such metrics. The sources
live in a one-dimensional subspace and the entire metric is uniquely determined
by them. We study in detail the structure of stationary and axisymmetric
metrics in four dimensions, and consider as an example the sources of the Kerr
black hole.
