Reliefs on the Voortrekker Monument at Pretoria, South Africa. The Voortrekker Monument is located just south of Pretoria in South Africa. This massive granite structure is prominently located on a hilltop, and was raised to commemorate the Voortrekkers who left the Cape Colony between 1835 and 1854. It was designed by the architect Gerard Moerdijk. On 8 July 2011, the Voortrekker Monument was declared a National Heritage Site by the South African Heritage Resource Agency.