 The furlong went from 600 old feet to 660 new feet, or from 200 old yards to 220 new yards.The acre went from 36,000 old square feet to 43,560 new square feet, or from 4,000 old square yards to 4,840 new square yards.The furlong was historically viewed as being equivalent to the Roman stade ("stadium"), which in turn derived from the Greek system.