  We present the public Monte Carlo photoionization and moving-mesh radiation
hydrodynamics code CMacIonize, which can be used to simulate the
self-consistent evolution of HII regions surrounding young O and B stars, or
other sources of ionizing radiation. The code combines a Monte Carlo
photoionization algorithm that uses a complex mix of hydrogen, helium and
several coolants in order to self-consistently solve for the ionization and
temperature balance at any given type, with a standard first order
hydrodynamics scheme. The code can be run as a post-processing tool to get the
line emission from an existing simulation snapshot, but can also be used to run
full radiation hydrodynamical simulations. Both the radiation transfer and the
hydrodynamics are implemented in a general way that is independent of the grid
structure that is used to discretize the system, allowing it to be run both as
a standard fixed grid code, but also as a moving-mesh code.
