Originally posted by warrenchmobile:

An old Army trick.

Put down one 2 x 2 meter floor tile. Position yourself just outside one edge of it. Press "C" to change to a walk. Cross the floor tile to just outside the opposite edge of the floor tile, counting the number of steps required. Remember that number.

To mark out an 80 x 80 meter area, walk in a straight line the number of steps it would take you to cross 40 2 x 2 meter tiles, turn 90 degrees, and walk the same number of steps in that direction. Voila, a rough 80 x 80 meter square.

This is only going to work with relatively flat areas where one can walk without having to chop down trees or pickaxe boulders. It should get you started, however.

Note: No, the Army doesn't use 2 x 2 meter floor tiles. The length of a standard Army marching stride is 30 inches; that is what a GI would use. The number of steps required to cross a 2 x 2 meter floor tile will give one the length a viking stadard walking stride.