It has been recently demonstrated that it is possible to construct
isochronous cosmologies, extending to general relativity a result valid for
non-relativistic Hamiltonian systems. In this paper we review these findings
and we discuss the Newtonian limit of these isochronous spacetimes, showing
that it reproduces the analogous findings in the context of non-relativistic
dynamics.Comment: arXiv admin note: text overlap with arXiv:1406.715