Transition metal oxides are well known for their emergent phases and novel electronic proper- ties evolving from the various competing many-body interactions through spontaneous symmetry- breaking. Additionally, the topological nature of band structures can give rise to new states of matter. In this project, we will use the possibilities of heterointerfacing — in particular electrostatic doping, band alignment, and strain engineering — to create and tune composite oxide materials with topolog- ical electronic states, typically in the presence of or assisted by electron correlations. This concerns the rich physics of pyrochlore and perovskite iridates that encompasses spin-orbit driven Mott insu- lators, topological superconductivity as well as Weyl and Dirac semimetals. By the same token, we will investigate bismuthates which display by virtue of their structural variants an interesting play- ground for tunable topological phases with predicted large band gaps. The experimental research program (sample growth by pulsed laser deposition, study of chemical and electronic structure by state-of-the-art x-ray spectroscopies) will benefit from a close collaboration with theory.