  We develop a method for constructing standard complexes which turns easy the
calculation of their algebraic invariants and, as well, the precise evaluation
of whether these complexes are embeddable or not in a 3-manifold. This method
applies to all familiar spines of 3-manifolds and, in particular, to the Bing
house with two rooms and the classical standard spine of the Poincar\'e sphere.
Finally, we exhibit a compact, connected standard complex which is embeddable
into an orientable 3-manifold, its fundamental group is $Z_{2}$ and it contains
a Klein bottle. This standard complex is the spine of a reducible 3-manifold
$M^3$, sum of a Seifert fiber space with a fake solid torus, whose universal
covering space $W^3$ is a closed and simply connected 3-manifold that cannot be
homeomorphic to $S^{3}$.
