Granular aluminum wire networks forming square arrays of N×N=1E6 nodes connected by strips of 8-μm long were fabricated with photolithographic techniques. For strip resistances of the order of 1 kΩ the superconducting transition of the network, as evidenced by AC conductance measurements is shown to be of the Kosterlitz-Thouless type. In a perpendicular magnetic field, flux quantization in the loops of the network leads to periodic oscillations of the magnetoconductance.