  The prospect of large extra dimensions and an effective theory of gravity at
around a TeV has interesting experimental consequences. In these models, the
Kaluza-Klein modes interact with Standard Model particles and these
interactions lead to testable predictions at present and planned colliders. We
investigate the effect of virtual exchanges of the spin-2 Kaluza-Klein modes in
the production cross-section of $t \bar t$ pairs at the Tevatron and the LHC
and find that the $t \bar t$ cross-section can be an effective probe of the
large extra dimensions. This enables us to put bounds on the effective
low-energy scale.
