The Sword of Goujian.
" Regarded as a state treasure, the Sword of Goujian was unearthed in September 1965 in Jiangling County, Hubei Province. The sword is as legendary to the Chinese people as King Arthur’s sword in the West. Having been buried for more than 2,000 years, upon discovery, the sword was very sharp and not rusty. What’s more, it contains some rhombic etchings and 11 concentric circles located only 0.2 millimeters apart at the tip of the handle. It seems almost impossible that such a marvel of supreme craftsmanship could have been constructed so long ago…." http://www.chinaculture.org/gb/en_curiosity/2004-06/23/content_47488.htm