The talk presents the frontiers and challenges in coupled-cluster computations of atomic nuclei. Resolution frontier: capturing multi-scale physics (i.e., binding energies that are 100s of MeV and excitation energies that are 100s of keV) is possible by breaking and restoring symmetries. Our computations reveal shape coexistence in ³⁰Ne. Mass frontier: computations of the doubly magic superheavy nucleus ²⁶⁶Pb show that its excitation spectrum is similar to that of ²⁰⁸Pb (i.e. a 3-minus excitation is below the lowest 2-plus state), and that ²⁶⁸Pb is unbound with respect to ²⁶⁶Pb. Finally, the talk introduces NuLattice, a Python software package for ab initio computations of atomic nuclei on lattices.