Abstract: Exceptional levels of quantum control and coherence are instrumental in quantum metrology and sensing. Atom interferometers are powerful in both probing fundamental physics and everyday sensing but have been limited to measurement times of a few seconds by using atoms in free fall. I will describe how we realize interferometers with atoms suspended for an unprecedented 70 seconds in an optical lattice. This method is particularly well suited for probing localized potentials. I will show how, for the first time, we (1) optimize the gravitational sensitivity of the lattice interferometer and (2) use a system of signal inversions and switches to suppress and quantify systematic effects. This enables us to measure the attraction of a miniature source mass with record accuracy of 6.2 nm/s2, less than a billionth of Earth’s gravity and four times as good as the best similar measurements with freely falling atoms. This performance demonstrates the advantages of lattice interferometry in fundamental physics measurements. I will then show how the lattice atom interferometer can overcome the limits of current atomic gravimeters for applications in the field. Finally, I will discuss prospects for next-generation lattice atom interferometers and applications in precision measurement and quantum inertial sensing.