Officially reported Archaeological sites for Missouri’s Department of Natural Resources.
(Thank you for respecting the sites.) 

These particular stones mark a survey by Antoine Soulard, Surveyor General of Upper Louisiana, at the corners of a land grant awarded to the Commandant of New Bourbon, Pierre Charles Dehault Delassus Deluziere in April of 1795. He and his family fled France during their Revolution and were awarded multiple land grants by the Spanish Government, later confirmed by the US Supreme Court. His son and heir, Carlos Dehault Delassus, was the last Spanish Lieutenant Governor of Upper Louisiana and Commandant at St. Louis during the Louisiana Purchase. 

Soulard’s surveys are within a collection, referred to as the Registre d’Arpentege, which contains over 700 surveys, dating from 1798 to 1806. The grounds for St. Louis’ historic Soulard Market that bears his name were willed to the city, in perpetuity, for use as a public market that continues today.