  We show that a 1D quantum wire with $23$ channels of interacting fermions has
a perfect metal phase in which all weak perturbations that could destabilize
this phase are irrelevant. Consequently, weak disorder does not localize it, a
weak periodic potential does not open a gap, and contact with a superconductor
also fails to open a gap. Similar phases occur for $N \geq 24$ channels of
fermions, except for $N=25$, and for $8k$ channels of interacting bosons, with
$k\geq 3$. Arrays of perfect metallic wires form higher-dimensional fermionic
or bosonic perfect metals, albeit highly-anisotropic ones.
