The spectrum of elliptic operators on a smooth domain encodes geometric information. One way of seeing this effect is via the asymptotics of the counting function, whose form is known as the Weyl law. Less is known about what happens in the case of geometric singularities, but it is an area of active research. This talk will cover the Weyl law of the Dirichlet to Nuemann map, both historical results for smooth domains, and recent results for piecewise smooth domains.