An illustrative modular manifold disclosed herein includes, among other things, a low-pressure manifold comprising a frac fluid outlet valve, wherein a fracturing fluid is adapted to be supplied from the low-pressure manifold via the frac fluid outlet valve to a suction side of a frac pump, and a high-pressure manifold comprising at least one frac fluid inlet valve, wherein the high-pressure manifold is adapted to receive, via the frac fluid inlet valve, a fracturing fluid discharged from the frac pump. In this example, the modular manifold also includes a support structure for mechanically supporting the low- and high-pressure manifolds and a plurality of height-adjustable support legs operatively coupled to the support structure.