It is extremely important to characterize the various bare copper surfaces in situ before any subsequent corrosion or deposition chemistry can be understood. In this paper, in situ Atomic Force Microscopy (AFM) was used to image the low-index faces of Cu single crystals in H2SO4 and HClO4 acidic solutions. Cu(100) surfaces exhibited potential-dependent c(2x2) adlayers in pH=1 solutions which were attributed to oxide (or hydroxide) overlayers. Images of Cu(1 10) obtained in pH 2.5-2.7 solutions revealed the growth of primarily  oriented (nxl) adlayer chain structures, where n is an integer. Preliminary measurements on Cu(111) did not reveal any adlayer structures between pH's of 1-3. The oxide monolayers on Cu(100) and Cu(110) crystals were observed in the thermodynamically forbidden region of the pH-potential phase diagram, which indicates that stable oxide adlayers develop prior to bulk oxide formation.