I will introduce the gravitational path integral and discuss some of its modern applications. Our first application will be to the black hole information paradox, where we will see that nontrivial gravitational saddles are important in exhibiting unitarity of black hole evaporation. Our second application will be to cosmological spacetimes, where we will see that big bang/big crunch spacetimes can be described analogously to the interior of black holes. Abstract: I will introduce the gravitational path integral and discuss some of its modern applications. Our first application will be to the black hole information paradox, where we will see that nontrivial gravitational saddles are important in exhibiting unitarity of black hole evaporation. Our second application will be to cosmological spacetimes, where we will see that big bang/big crunch spacetimes can be described analogously to the interior of black holes.