  We consider an extension of the Randall-Sundrum model with three parallel
3-branes in a 5-dimensional spacetime. This new construction, apart from
providing a solution to the Planck hierarchy problem, has the advantage that
the SM fields are confined on a positive tension brane. The study of the
phenomenology of this model reveals an anomalous first KK state which is
generally much lighter than the remaining tower and also much more strongly
coupled to matter. Bounds on the parameter space of the model can be placed by
comparison of specific processes with the SM background as well as by the
latest Cavendish experiments. The model suggests a further exotic possibility
if one drops the requirement of solving the hierarchy problem. In this case
gravity may result from the exchange of the ordinary graviton plus an
ultralight KK state and modifications of gravity may occur at both small and
extremely large scales.
