  The development of quantum-gas microscopes has brought novel ways of probing
quantum degenerate many-body systems at the single-atom level. Until now, most
of these setups have focused on alkali atoms. Expanding quantum-gas microscopy
to alkaline-earth elements will provide new tools, such as SU(N)-symmetric
fermionic isotopes or ultranarrow optical transitions, to the field of quantum
simulation. Here, we demonstrate the site-resolved imaging of a $^{84}$Sr
bosonic quantum gas in a Hubbard-regime optical lattice. The quantum gas is
confined by a two-dimensional in-plane lattice and a light-sheet potential,
which operate at the strontium clock-magic wavelength of 813.4 nm. We realize
fluorescence imaging using the broad 461 nm transition, which provides high
spatial resolution. Simultaneously, we perform attractive Sisyphus cooling with
the narrow 689 nm intercombination line. We reconstruct the atomic occupation
from the fluorescence images, obtaining imaging fidelities above 94%. Finally,
we realize a $^{84}$Sr superfluid in the Bose-Hubbard regime. We observe its
interference pattern upon expansion, a probe of phase coherence, with
single-atom resolution. Our strontium quantum-gas microscope provides a new
platform to study dissipative Hubbard models, quantum optics in atomic arrays,
and SU(N) fermions at the microscopic level.
