  So far the physics of moir\'e graphene bilayers at large, incommensurate
rotation angles has been considered uninteresting. It has been held that the
interlayer coupling in such structures is weak and the system can be thought of
as a pair of decoupled single graphene sheets to a good approximation. Here, we
demonstrate that for large rotation angles near commensurate ones, the
interlayer coupling, far from being weak, is able to completely localize
electrons to within a large scale, geometrically frustrated network of
topologically protected modes. The emergent geometric frustration of the system
gives rise to completely flat bands, with strong correlation physics as a
result. All of this arises although in the lattice structure no large scale
pattern appears to the unguided eye. Sufficiently close to commensuration the
low-energy physics of this remarkable system has an exact analytical solution.
