  Under a weak assumption of the existence of a geodesic null congruence, we
present the general solution of the Einstein field equations in three
dimensions with any value of the cosmological constant, admitting an aligned
null matter field, and also gyratons (a matter field in the form of a null dust
with an additional internal spin). The general local solution consists of the
expanding Robinson-Trautman class and the non-expanding Kundt class. The
gyratonic solutions reduce to spacetimes with a pure radiation matter field
when the spin is set to zero. Without matter fields, we obtain new forms of the
maximally symmetric vacuum solutions. We discuss these complete classes of
solutions and their various subclasses. In particular, we identify the
gravitational field of an arbitrarily accelerating source (the Kinnersley
photon rocket, which reduces to a Vaidya-type non-moving object) in the
Robinson-Trautman class, and pp-waves, vanishing scalar invariants (VSI)
spacetimes, and constant scalar invariants (CSI) spacetimes in the Kundt class.
