  We present a connection between two known solutions to the strong-CP problem:
the standard introduction of axions and the extra-dimensional one, relying on
topological arguments. Using an equivalent lower-dimensional set-up with a
warped extra-dimension but without adding any new fields, it is shown that an
additional light degree of freedom appears. Like an axion, it couples to the
topological charge density via Fermionic loop corrections. Its decay constant
is related to the geometry of the extra dimension and is suppressed by the
warping scale.
