This plaque is at the Ulysses S. Grant National Historic Site in Grantwood Village, MO, a close-by suburb of St. Louis. It honors the homestead that is still intact that President Grant lived prior to his becoming the general in the Civil War and subsequently, a US President. The home was restored by the US National Parks Service in the 90's I believe.
There is a fascinating story about the family conflict in regards to slavery in the mid-1800's as this farm was owned by his father-in-law, Frederick Dent, a slave holder. Grant. originally from Ohio, came to St Louis as a soldier, stationed at Jefferson Barracks, about 10 miles from here. Here, he met his future wife, Julia Dent, the daughter of Frederick. He personally was against slavery but married into a family that had many slaves working their farm on this exact site. The story is much longer and more complex but this is a good start to get you looking into it.
Here is the link to the NPS website for the Historic Site.
Ed Brimer
St. Louis, MO