Ballistic walls include a plurality of interlocking blocks formed of a bullet-resistant material, a first portion of the periphery of each block having a protruding tongue, a second portion of the periphery of each block defining a groove sized to receive the tongue, and the tongues and grooves of adjacent blocks being mated to each other to form an interlocked structure. Each block may be formed of a stack of panels having a first surface panel, a second surface panel, and an interior panel, wherein the interior panel is offset from the first and second surface panels to form the tongues and to define the grooves. Each block may be formed of a stack of five panels offset from each other. The blocks may be arranged in a running bond, such that the vertical seams of one course are offset from the vertical seams of an adjacent course.