  The QCD axion is one of the most compelling solutions of the strong CP
problem. There are major current efforts into searching for an ultralight,
invisible axion, which is believed to be the only phenomenologically viable
realization of the QCD axion. Visible axions with decay constants at or below
the electroweak scale are believed to have been long excluded by laboratory
searches. Considering the significance of the axion solution of the strong CP
problem, we revisit experimental constraints on QCD axions in the O(10 MeV)
mass window. In particular, we find a variant axion model that remains
compatible with existing constraints. This model predicts new states at the GeV
scale coupled hadronically, and a variety of low-energy axion signatures, such
as rare meson decays, nuclear de-excitations via axion emission, production in
$e^+e^-$ annihilation and fixed target experiments. This reopens the
possibility of solving the strong CP problem at the GeV scale.
