On 5 April 2017, Keith Martin, who heads up the heritage community in Modderfontein, unveiled the first two heritage plaques to be erected in the area. This was done in conjunction with the Thornhill Homeowners Association and under the auspices of Joburg Heritage. The plaques are positioned at significant sites within Thornhill Estate.
One site commemorates the first granite rocks to be quarried at Modderfontein. These are located on a specially built platform at 8 Brussels Ave.