Alaric, King of the Visigoths, sacked Rome in 410, and then died shortly afterward, near the river Busento, in southern Italy. His soldiers had his slaves divert the flow of the river in order to bury him, along with his gold and jewels. Then they restored the river to its original course. The slaves who had buried him were then killed. His body has never been found.
“The burial of Alaric in the bed of the Busentinus,” 1895, via Wikimedia
Busento River, By Salatino (Own work) [GFDL (www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons
During the early 19th century construction of the cathedral of St. Isaac in St. Petersburg, Russia, workers gilded the domes with a gold-mercury amalgam. Sixty workers died of mercury poisoning.