Inside floor radius of rath: 45 cubits / 27 rods (Inside diameter: 90 cubits / 54 rods)

Edge of rath circle radius: 54 cubits

Edge of fosse radius: 66 cubits

Top of the longstone is 166 rods above sea level.

Where:
1 Rod = 3.475 imperial feet = 41.7 inches = 1.059 meters.
1 Cubit = 2.085 feet.
Ratio: 1 Rod = 1.666 cubits.

These were used by ancient Egyptians and the Jewish architects of the Temple. The earth's polar radius is 6,000,000 rods (3,949.71 miles). Modern satellite data shows it to be actually 3,949.88 miles; not bad.

How do these link to the more famous sky observatory at Newgrange in Co Meath? It is 75 rods in diameter and the shaft that allows light in at the winter solstice is 17 rods long. Built c.3150BC, it has been computed that its solstice alignment was accurate to half a degree, or 1 in 720.

At Stonehenge the lintels are 1 rod wide and 1 rod times ¼ (pi) long on their curved outer sides. The internal radius is 14 rods so the external diameter is 30 rods = 50 cubits.

See also:
www.stonelight.ie/archive/arch49.html
www.megalithomania.com