  It is almost 80 years since Hans Bethe described the level density as a
non-interacting gas of protons and neutrons. In all these years, experimental
data were interpreted within this picture of a fermionic gas. However, the
renewed interest of measuring level density using various techniques calls for
a revision of this description. In particular, the wealth of nuclear level
densities measured with the Oslo method favors the constant-temperature level
density over the Fermi-gas picture. From the basis of experimental data, we
demonstrate that nuclei exhibit a constant-temperature level density behavior
for all mass regions and at least up to the neutron threshold.
