A rigid modular container includes a floor and an opposite lid, and between the floor and lid opposite rigid rectilinearly-shaped first and second panels, and oppositely disposed rigid rectilinearly-shaped third and fourth panels extending from and between the first and second panels. The panels are removably mounted to the floor. The side edges of adjacent panels are removably mounted to each other as by bolting so that the side edges of the third and fourth panels abut the side edges of the first and second panels. Fastener bracing means such as bolt bracing are mounted to the side edges of the panels and are aligned between adjacent the panels so that fastener receiving apertures therethrough provide for rigid bracing of rigid fasteners such as bolts mounted through and between the fastener bracing means on the adjacent panels. Rigid fasteners such as bolts may thus be mounted through the fastener bracing means on the adjacent the panels.