Baker then sold it to Dr. Joseph W. Robertson in 1848. The Robertson family (his wife and 11 children - 5 girls and 6 boys) and their descendants lived in the house for about a century. Robertson’s last remaining daughters, Miss Lillie Robertson, who died in 1939, and Miss Sarah Robertson, who died in 1940, in their later years opened the house to the public calling it “Old French Embassy”. Both of them were very interested in the preservation of the house, and allowed in 1934 the house to be surveyed for the Historic American Building Survey (HABS). Following their deaths, the house was sold to the state of Texas in 1950 which then appointed the Daughters of the Republic of Texas (DRT) as the property’s custodian. As state above, the DRT opened the French Legation Museum to the public in 1956. Today, the Museum is devoted to sharing the site’s past and rich cultural history of Texas with the public.
The building was added as a Recorded Texas Landmark in 1967, listed in the National Register of Historic Places in 1969 and in 1974 designated as a State Historical Landmark. In 1981, the site was designated as a Texas State Archaeological Landmark.