Lattice structures containing interconnected 3-dimensional solid frames with open pore channels are promising structural materials for dynamic and extreme conditions as they show superior strengths and energy absorption capability during deformation. The mechanical performance of lattice structures can be improved even more by introducing the “smaller is stronger” size effect. However, typical microfabrication using UV lithography is limited to 2.5D geometries, as such, fabricating complex architectures such as microlattices is not possible. In this study, we report the fabrication of metal microlattices via an additive micromanufacturing process based on localized electrodeposition. As a case study, we fabricated the pure copper microlattice structures and examined the structure, microstructure, and mechanical properties. The structure of microlattices was characterized via NanoCT and near-ideal connectivity between the nodes and struts was identified. The microstructural characterization was conducted using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses, showing that the microlattices are ultrafine-grained with a high fraction of nanotwin boundaries. Subsequently, we investigated the mechanical properties of the copper microlattices at a wide range of strain rates from 0.001/s to 100/s and various temperature conditions (-150 and 25 °C) using a piezo-based in situ SEM micromechanical testing setup. This study demonstrates that complex 3-dimensional metal architectures can be fabricated on a micron scale and such architectures exhibit superior mechanical properties suitable for dynamic and extreme mechanical loading conditions.