  Using a phenomenological \={K}N interaction combined with the method of
Antisymmetrized Molecular Dynamics., we predict that few-body double-\kbar
nuclei, such as ppK$^-$K$^-$ and ppnK$^-$K$^-$, as well as single-\kbar nuclei,
are tightly bound compact systems with large binding energies and ultra-high
nucleon densities. We point out that these \kbar nuclear clusters can be
produced as residual fragments in relativistic heavy-ion collisions and that
their invariant masses can be reconstructed from their decay particles.
