The low-temperature elementary spin excitations in the AFM molecular wheel Fe₁₈ were studied experimentally by inelastic neutron scattering and theoretically by modern numerical methods, such as dynamical density matrix renormalization group or quantum Monte Carlo techniques, and analytical spin-wave theory calculations. Fe₁₈ involves eighteen spin-5/2 Fe^III ions with a Hilbert space dimension of ∼10¹⁴, constituting a physical system that is situated in a region between microscopic and macroscopic. The combined experimental and theoretical approach allowed us to characterize and discuss the magnetic properties of Fe₁₈ in great detail. It is demonstrated that physical concepts such as the rotational-band or L and E-band concepts developed for smaller rings are still applicable. In particular, the higher-lying low-temperature elementary spin excitations in Fe₁₈ or AFM wheels, in general, are of discrete antiferromagnetic spin-wave character.