  The detailed morphology of the interstellar medium (ISM) in the central
kiloparsec of galaxies is controlled by pressure and gravitation. The
combination of these forces shapes both circumnuclear star formation and the
growth of the central, supermassive black hole. We present visible and
near-infrared Hubble Space Telescope images and color maps of 123 nearby
galaxies that show the distribution of the cold ISM, as traced by dust, with
excellent spatial resolution. These observations reveal that nuclear dust
spirals are found in the majority of active and inactive galaxies and they
possess a wide range in coherence, symmetry, and pitch angle. We have used this
large sample to develop a classification system for circumnuclear dust
structures. In spite of the heterogeneous nature of the complete sample, we
only find symmetric, two-arm nuclear dust spirals in galaxies with large scale
bars and these dust lanes clearly connect to dust lanes along the leading edges
of the large scale bars. Not all dust lanes along large scale bars form two arm
spirals, however, and several instead end in nuclear rings. We find that
tightly wound, or low pitch angle, nuclear dust spirals are more common in
unbarred galaxies than barred galaxies. Finally, the extended narrow line
region in several of the active galaxies is well-resolved. The connection
between the ionized gas and circumnuclear dust lanes in four of these galaxies
provides additional evidence that a significant fraction of their extended
narrow line region is ambient gas photoionized in situ by the active nucleus.
In a future paper, we will use our classification system for circumnuclear dust
to identify differences between active and inactive galaxies, as well as barred
and unbarred galaxies, in well-matched subsamples of these data.
