Abstract: A building module for use in constructing a blast-resistant modular building. The building module includes a pair of parallel skid members and a rectangular body mounted on the skid members. The body includes sides, a roof and a floor defining an interior of the building module. A first side of the body includes an opening. A flange co-extensive with opposite sides and a top of the first side includes a plurality of holes for receiving respective bolt-type fasteners. Alignment pins project outwardly from the body proximal a bottom of the first side, for engaging corresponding alignment holes of the other building module. Each alignment pin includes a cylindrical portion at a base end of the pin, and a tapered portion.