  We construct a rational integrable system (the rational top) on a coadjoint
orbit of ${\rm SL}_N$ Lie group. It is described by the Lax operator with
spectral parameter and classical non-dynamical skew-symmetric $r$-matrix. In
the case of the orbit of minimal dimension the model is gauge equivalent to the
rational Calogero-Moser (CM) system. To obtain the results we represent the Lax
operator of the CM model in two different factorized forms -- without spectral
parameter (related to spinless case) and another one with the spectral
parameter. The latter gives rise to the rational top while the first one is
related to generalized Cremmer-Gervais $r$-matrices. The gauge transformation
relating the rational top and CM model provides a classical rational version of
the IRF-Vertex correspondence. From a geometrical point of view it describes
the modification of ${\rm SL}(N,\mathbb C)$-bundles over degenerated elliptic
curve. In view of Symplectic Hecke Correspondence the rational top is related
to the rational spin CM model. Possible applications and generalizations of the
suggested construction are discussed. In particular, the obtained $r$-matrix
defines a class of KZB equations.
