  Hubble Space Telescope observations of the central kiloparsec of AGN have
revealed a wealth of structure, particularly nuclear bars and spirals, that are
distinct from analogous features in the disks of spiral galaxies. WFPC2 and
NICMOS images of a large sample of AGN observed at high spatial resolution make
it possible to quantify the frequency and detailed properties of these
structures. Nearly all AGN have nuclear spiral dust lanes in the central
kiloparsec, while only a small minority contain nuclear bars. If these nuclear
dust spirals trace shocks in the circumnuclear, gaseous disks, they may
dissipate sufficient angular momentum to fuel the active nucleus.
