Thornhill was the family residence of Rose, Penelope, and Cheryl Blossom, as well as Clifford and Jason Blossom before their deaths. It was a large old mansion set on an expansive estate that included a cemetery where many members of the family had been buried.
Following the reveal that Jason Blossom had been murdered by his own father, Clifford, and Cliff's subsequent suicide, the residence was set a blaze by Cheryl and destroyed, as Cheryl saw it as a way to start over fresh with a new beginning for their family due to their past history. However, the barns on the estate are still inhabitable as Penelope and Claudius have taken up residence.
After his body is found, Jason Blossom is buried in the cemetery on Thornhill's grounds. Originally, his parents had buried an empty casket.
The Blossom family motto, as inscribed on the mansion's front gates is "Radices Currere Abyssi" which translates as “Roots Run Deep".
Also on the front gates are roman numerals MCMXLI, 1941, likely the year the house was built. (Also the year of Archie first appeared in Pep Comics #22)
Located within Thornhill's cemetery are headstones belonging to Joshua Elliot McKinney, a Townsend, and a couple named Joe and Martha Fields. Nothing else is known about these people except for what is engraved on their headstones (such as Joshua McKinney being only 5 years old when he died).