Monolayers of a large tetralactam macrocycle were prepared by vacuum sublimation on the Au(111) surface and investigated by scanning tunnelling microscopy. The macrocycles form three different highly ordered monolayer structures α, β, and η. The α and β structure are stable at room temperature and can be understood as two dimensional networks which are held together by hydrogen bonds between the next neighbour molecules. These structures were described in detail before [Kossev et al., Adv. Mat. 17, 513 (2007)]. The third structure, which is described here, is only observed after heating at 400 K and rapid cooling to low temperatures. It consists of chiral aggregates, composed of three molecules. These aggregates are either left or right handed. The surface is covered by a racemic mixture of long range ordered domains with either left or right handed aggregates.