Once in a while, a discovery comes along that opens up uncharted paths of inquiry. The discovery of atomically thin crystals, starting with graphene and followed up with dozens in the van der Waals family of compounds, has changed the way we think about materials. This new class of designer materials is making it possible to tune and control electronic properties without changing chemical composition, through alternative means such as superposing different layers, misaligning them, inducing strain, etc. In this talk I will describe highlights from this rapidly evolving field, from its serendipitous inception, to the discovery of correlated electron phases in twisted layers.