Micromorphology of phase separated Langmuir-Blodgett (LB) films is investigated by atomic force microscopy from submicrometer scale up to 100 mum scale. Several novel phenomena are revealed : (a) the existence of grains with the size of 20-100 nm in diameter in the liquid expanded phase; (b) the existence of a rough domain boundary with fingerlike structures and (c) an inhomogeneous distribution of holelike defects in the liquid condensed domains. Aging effects are studied systematically, which give the hint for the existence of water on transferred LB films. The results are relevant to the understanding of the early stages of the domain formation and the two-dimensional nucleation processes.