  We extract the long-range gravitational potential between two scalar
particles with arbitrary masses from the two-to-two elastic scattering
amplitude at 2nd Post-Minkowskian order in arbitrary dimensions. In contrast to
the four-dimensional case, in higher dimensions the classical potential
receives contributions from box topologies. Moreover, the kinematical relation
between momentum and position on the classical trajectory contains a new term
which is quadratic in the tree-level amplitude. A precise interplay between
this new relation and the formula for the scattering angle ensures that the
latter is still linear in the classical part of the scattering amplitude, to
this order, matching an earlier calculation in the eikonal approach. We point
out that both the eikonal exponentiation and the reality of the potential to
2nd post-Minkowskian order can be seen as a consequence of unitarity. We
finally present closed-form expressions for the scattering angle given by
leading-order gravitational potentials for dimensions ranging from four to ten.
