Both the exceptional high symmetry of the C-60 molecule and the molecular nature of the solid determine the conditions for a dipole forbidden lowest excited electronic manifold which extends from 1.8eV to about 3eV. The one-photon activity in this spectral range is due to the Herzberg-Teller vibronic coupling between these forbidden states and higher T-1u excitations. The location of the lowest excited singlet state is performed by two non-linear spectroscopic techniques. First we report on the third harmonic generation spectrum of C-60 thin film. Fitting of the relatively large number of experimental points with a three-level model suggests the presence of a low lying forbidden state at 1.87 eV. Preliminary data of two-photon excitation spectroscopy of C-60 single crystal confirm this finding and allows to locate the level at 1.846 eV. This is in complete agreement with the assignment to a T-1g excited state based on the photoluminescence experiments presented by Guss et al. In this issue.