We report on a method to fabricate a porous two dimensional (2D) array of porphyrins on c(2×2)N/Cu(001) with pore sizes larger than 5 nm, larger than the reported sizes for hydrogen-bonded or coordination porous organic networks. When deposited on the square nanopattern created by partial nitridation of the Cu(001) surface, the porphyrin molecules prefer to adsorb on clean copper instead of adsorbing on the CuN islands, forming a porous 2D array. This nanopatterning technique can be straightforwardly extended to other molecular species to form the pore walls since its working principle only depends marginally on the nature of the intermolecular interactions.