  Despite their diversity, many of the most prominent candidate theories of
quantum gravity share the property to be effectively lower-dimensional at small
scales. In particular, dimension two plays a fundamental role in the finiteness
of these models of Nature. Thus motivated, we entertain the idea that spacetime
is a multifractal with integer dimension 4 at large scales, while it is
two-dimensional in the ultraviolet. Consequences for particle physics, gravity
and cosmology are discussed.
