  We analyze the localization properties of two dimensional systems based on
partite lattices with a basis. Contrary to standard results, we find that a
band of critical states emerges for systems in the unitary class A preserving
spin symmetry when disorder is unevenly distributed over the basis atoms. The
critical metal arises when the less disordered sublattice is connected and has
time reversal symmetry broken. The unexpected robustness to disorder presented
here is an appealing result which can be measured in optical lattices.
