The A-site ordered perovskites CaCu3B4O12, which are derived from the conventional ABO3 perovskites, exhibit intriguing electronic and magnetic properties due to the competing interactions among spin, charge, and lattice degrees of freedom. In this work, with the objective of examining the role of Cu, we have investigated CaCu3Ti4O12 and CaCu3Zr4O12 and presented the source for the crystallization of A-site ordered perovskite from the conventional ABO3 perovskite and the underlying mechanism leading to the stabilization of non-trivial and experimentally established G-type antiferromagnetic (G-AFM) ordering in these systems. The electronic structure calculations supplemented with phonon studies reveal that the formation of A-site ordered perovskite is driven by the Jahn-Teller distortion of CuO12 icosahedron complexes. The crystal orbital Hamilton population analysis and magnetic exchange coupling interactions estimated using the spin dimer analysis infers that the nearest and next-nearest neighbour interactions (J1 and J2) are direct and weakly ferromagnetic whereas the third-neighbour interaction (J3) is strong and antiferromagnetic, driven by the indirect superexchange interaction. The structural geometry reveals that the stabilization of G-AFM requires J1 2J2 and J1 2J3. The estimated Neel temperature (TN) using the on-site Coulomb repulsion U ≈ 7 eV is in well agreement with the experimentally observed TN (25 K). The magnetic ordering is found to be robust against the uniform pressure and epitaxial strain. In the second half of the presentation we will present our future research plan focusing on the quantum states of A-site ordered perovskites.