When the first STM images appeared, they were a revelation. No one had ever seen individual atoms before. Since then, various technologies have pushed imaging to mind-boggling extremes. The latest is the announcement from FEI that they've resolved the dumbbell structure of germanium, a 0.14 nm feature. Wow.
(Both silicon and germanium have a pair of atoms, or dumbbell, at each lattice point. Germanium is larger, so resolving it is slightly easier. Slightly.)