Square nails have been found by archaeologists and dated back to 3000 B.C. These nails were made by hand by blacksmiths. The earliest nails were made of iron, which rusts and disintegrates over time.
Square nails were made by hammering a rod into a square shape and tapering it towards the end. The taper was cut off and the blacksmith then inserted the rod into a nail-heading tool and pounded the top of the nail into the head.
As of 2014, square nails are still used when restoring antique furniture. Square nails often have decorative heads when used in furniture.