  In this paper, we construct a class of collapsing spacetimes in vacuum
without any symmetries. The spacetime contains a black hole region which is
bounded from the past by the future event horizon. It possesses a Cauchy
hypersurface with trivial topology which is located outside the black hole
region. Based on existing techniques in the literature, the spacetime can in
principle be constructed to be past geodesically complete and asymptotic to
Minkowski space. The construction is based on a semi-global existence result of
the vacuum Einstein equations built on a modified version of the a priori
estimates that were originally established by Christodoulou in his work on the
formation of trapped surface, and a gluing construction carried out inside the
black hole. In particular, the full detail of the a priori estimates needed for
the existence is provided, which can be regarded as a simplification of
Christodoulou's original argument.
