Add an industrial touch to your urban garden with concrete block pillars. These sturdy pillars can be used to create a stylish and modern gateway. Stack the concrete blocks to your desired height and secure them together with mortar. The raw and minimalist look of the concrete blocks complements the urban aesthetic. You can leave them as is or paint them in a color that matches your outdoor decor. Top the pillars with decorative pots or lanterns to enhance the visual appeal.