The study of physical phenomena at the nanoscale has been a subject of intense research, with many new discoveries emerging in dimensions ranging from several to one hundred nanometers. Recently, moiré patterns in two-dimensional (2D) materials have been found to offer near-perfect nanometer-scale electronic superlattices, which led to discoveries of exciting quantum phenomena in a variety of moiré heterostructures. In this colloquium, I will discuss my work using the moiré superlattice as a building block to develop correlated systems. Specifically, I have observed a correlated interlayer exciton insulator in a double-layer heterostructure, which consists of a Mott insulator and a band insulator. Furthermore, I have engineered the correlated insulator in bilayer graphene using a remote Coulomb superlattice. This technique is applicable to any 2D materials hosting a 2D electron gas, offering a new route for in-situ control of correlated quantum phenomena in a wide range of 2D systems.