Individually trapped neutral atoms provide a promising platform to engineer quantum many-body systems in a controlled, bottom-up approach. They can be readily manipulated in large numbers and interact strongly when excited to Rydberg states. In particular, this approach allows to arrange atoms in arbitrary 2D geometries. In this talk I will show that the ground state phase diagram of such 2D atom arrays can host a plethora of different phases, depending on the atom arrangement. These include various conventionally ordered phases that break lattice symmetries, as well as topologically ordered phases such as spin liquids, which can not be characterized by a local order parameters. I will discuss how these states can be prepared and probed, and highlight potential future applications of this approach.