  We report on the site-resolved observation of characteristic states of the
two-dimensional repulsive Fermi-Hubbard model, using ultracold $^{40}$K atoms
in an optical lattice. By varying the tunneling, interaction strength, and
external confinement, we realize metallic, Mott-insulating, and band-insulating
states. We directly measure the local moment, which quantifies the degree of
on-site magnetization, as a function of temperature and chemical potential.
Entropies per particle as low as $0.99(6)\,k_B$ indicate that nearest-neighbor
antiferromagnetic correlations should be detectable using spin-sensitive
imaging.
