The anharmonic force field of benzene has been calculated using a finite difference method by means of density functional theory (DFT) with the B3LYP functional and a TZ2P atomic orbitals basis set, and compared to the field calculated by Maslen [J. Chem. Phys. 97, 4233 (1992)]. The vapor phase infrared (IR) spectra of benzene (natural isotopic mixture) and of C-12-benzene have been recorded from 450 to 6000 cm(-1), at resolutions varying from 0.05 to 0.008 cm(-1), and at various path lengths (0.18/42 m). The parallel bands nu(11), nu(4)+nu(12), nu(5)+nu(12), nu(2)+nu(11), and nu(7)+nu(16), using the Wilson numbering, with their accompanying hot bands, have been analyzed and their origins determined to test our computed anharmonic force field. The Raman spectra of gas-phase benzene have been also recorded at medium resolution (similar to 0.7 cm(-1)) using an argon laser (line at 514.5 nm) with a power of 0.8 W and a multipass cell. In this work we compare the experimental and the theoretical frequencies and band profiles of the parallel nu(1), nu(2), 2 nu(16), 2 nu(4), and 2 nu(14) and of the corresponding hot bands, taking into account the l-vibrational doubling and all Fermi resonances within 100 cm(-1). By comparison with experiment, the DFT B3LYP is shown to be more accurate than the self-consistent field (SCF): the fundamentals are calculated with a mean absolute error of 10.7 cm(-1) and most of the spectroscopic constants are in better agreement with the experimental values.