Here it is, the 23th and last UNESCO site from the USA. The Monumental Earthworks of Poverty Point were added to the WHS list in 2014.
The card was sent by Donna.
Monumental Earthworks of Poverty Point owes its name to a 19th-century plantation close to the site, which is in the Lower Mississippi Valley on a slightly elevated and narrow landform. The complex comprises five mounds, six concentric semi-elliptical ridges separated by shallow depressions and a central plaza. It was created and used for residential and ceremonial purposes by a society of hunter fisher-gatherers between 3700 and 3100 BP. It is a remarkable achievement in earthen construction in North America that was unsurpassed for at least 2,000 years. - in: http://whc.unesco.org/en/list/1435