Quantitative characterization of energy landscapes at buried interfaces is essential for assessing their functionality. This Perspective highlights recent developments in reconstructing internal potential profiles based on hard x-ray photoemission experiments that have proved to be a rich source of information. We show that band-edge profiles can be reconstructed by interpreting core-level photoelectron spectra using a comprehensive search for the best-fit set of associated layer-resolved spectra. The use of hard x-rays allows heterostructures to be probed over length scales comparable to relevant electronic screening lengths. Significantly, this information takes our understanding of such systems to a new level that is not currently achievable using any other experimental technique.