Transmission electron micrographs of thin evaporated gold films were analyzed by computer. For length scales above 10 nm, the irregular connected clusters show a perimeter linearly proportional to area. Near the percolation threshold the large-scale power-law correlations and area distributions are consistent with the scaling theory of second-order phase transitions. Geometrically, the boundary of all clusters is a fractal of dimension D=2 while individual boundaries are of fractal dimension DC 1.9. © 1982 The American Physical Society.