Epitaxial growth of complex oxides enables the fabrication of materials layer by layer in fashion design, allowing for intervention during film growth and facilitating the creation of artificial materials and unique interfaces. Epitaxial layers are influenced by the boundary conditions, leading to changes in their properties due to strain, polar discontinuities, and octahedral connectivity (mis)matching. This sensitivity provides a unique opportunity to engineer the materials' structure and two-dimensional properties of materials at the interfaces. Thus, advanced epitaxy has become a key research tool for understanding materials by disentangling different structural parameters. Using molecular-beam epitaxy (MBE), pulsed laser deposition (PLD), and thermal laser epitaxy (TLE) techniques, we grow ultra-thin films and heterostructures of complex oxides to create new physical properties at the nanoscale. With the unmatched support of atomic resolution STEM imaging and spectroscopy, the realization of oxide epitaxy has advanced over the past decades.