Do-It-Yourself Cobblestone Grids

Square a 10-by-10 area with a tape measure. Drive 1/2-inch rebar in the ground at each corner of the 10-by-10 box grid, leaving the rebar sticking up 6 inches.

Measure down from the top of the rebar 1 inch and place a mark. Connect the four corners of this 10-by-10 square grid with nylon string. Place the string at the correct height on the pencil marks and stretch it tightly.

Remove 4 inches of soil from inside the grid. Loosen the dirt with a pick axe and remove it with a shovel. Measure the dirt height with a tape measure to keep a uniform depth.

Mix Portland cement and brick sand in a wheelbarrow. Add eight shovels of sand and 1/2 bag of cement to the wheelbarrow, and combine the mixture with a hoe. Add 3 gallons of water, and blend the mixture until you achieve a pancake batter consistency.

Spread the mortar down onto the ground inside the grid. Scoop up the mortar from the wheelbarrow with a mason's trowel and pile it inside the grid. Lay out a 24-inch mortar bed, working from one corner of the grid.

Press the cobblestone into the mortar bed, aligning the stone with the string height on the perimeter of the grid. Install the cobblestone as you would a jigsaw puzzle, fitting each stone against another as its shape allows.

Press the stones tight against each other. Chip the stones as necessary to make them fit into smaller areas. Continue to work in 24-inch sections, installing the cobblestones around the perimeter first and in the center last.