Lucille Davie wrote a fantastic piece on Johannesburg's oldest buildings in the early 2000s. Using her research as well as work done by the community here is a powerful list. If you have any buildings to add please do so in the comments section below. Feel free to correct any of the dates if applicable.

NB Note: There are a number of archaeological sites around Johannesburg with evidence of early structures (Northcliff, Klipriviersberg, Lonehill, Melville Koppies, Linksfield etc.). Feel free to add details.

1. 1852: Original Bezuidenhout Farmhouse, Bezuidenhout Valley - via City of Joburg
2. 1860: Hy Many House, Randpark Ridge
3. 1861: The Gables, Weltevreden Farm House - courtesy Brendan Hart
4. 1863: Main Bezuidenhout Farmhouse, Bezuidenhout Valley
5. 1871: Edgson's Store, Muldersrift - courtesy Rod Kruger
6. 1885: Walker's Cottage (Ruins - built for the Struben Brothers), Constantia Kloof courtesy Rod Kruger
7. 1886: Klipfontein Farm, Overlooking Orange Grove Norwood - courtesy Guy
8. 1887: Emmarentia Farmhouse, Emmarentia
9. ​1887: Building on the corner of Rockey and Davies Street, Doornfontein (confirmation needed)
10. 1887: Booysens Hotel (confirmation needed) - courtesy Jacques Stoltz (JHF spreadsheet says 1890)
11. 1888: Remains of Bettelheim House, Doornfontein - research by Oscar Norwich
12. 1889: St Mary's the Less, Jeppestown
13. 1890: Forester's Cottage, Parktown
14. 1891: House Hains, Yeoville - courtesy Brendan
15. 1892: Fashion Kapitol Cottage, Inner City - courtesy Brendan
16. 1892: Kimberley House Facade, Inner City
17. 1892: The Fort, Constitution Hill
18. 1893: Jeppestown lodge in Hans Street via Marc Latilla
19. 1895: 12 Park Lane, Parktown - courtesy Brendan Hart
20. 1895: Three Castles Building, Inner City (references have been found for 1894, 95, 96, 97 & 98)
21. 1895: Another Fashion Kapitol Cottage, Inner City - courtesy Brendan Hart
22. 1895 The old Marionite Church (formerly Dutch Reformed Church) on Mint Road in Fordsburg (via johannesburg1912)
23. 1895/96: The Thrupps in Maddison Street - courtesy Marc Latilla
24. 1896: Sunnyside, Parktown (some sources put it at 1894) - courtesy Nick
25. 1896: Grand Station Hotel (Norman's Grill) - courtesy Marc Latilla
26. 1896: The View, Parktown
27. 1896: Windybrow, Hillbrow
28. 1896: 32-34 Alexander Street Ferreiras Dorp - via JHF researchers
29. 1896: Kazerne Buildings, Diagonal Street
30. 1896/97: Old Park Station - via Jacques Stoltz
31. 1896/97: Markhams
32. 1897: Manchester Hotel (demolished)
33. 1897: Victory House
34. 1897: Rissik Street Post Office
35. 1897: Operating Theatre, Hillbrow Health Precinct
36. 1897: Christ Church, Mayfair - courtesy Derek
37. 1897: Jeppe Post Office - courtesy Marc
38. 1897: Kensington Sanitorium - courtesy Marc
39. 1897: Ranath House, Joubert Street
40. 1897: Penlan Building, Eloff Street
41. 1897: Melrose House - courtesy Brendan
42. 1897: Transvaal Chinese United Club - JHF survey via Jacques Stoltz
43. The old Presbyterian Church on Mint Road Fordsburg (noe Divine Bakery) by Architect Granger Fleming via Brendon Hart
44. 1898: Villa Mayfair (cnr 9th Battery Mayfair) - courtesy Derek
45. 1899: Cosmopolitan Hotel - courtesy Marc Latilla

Additions without a specific date:

1. Late 19th Century ZAR Period: Old Prison and Gaoler's House, Roodepoort - courtesy Brendan and Rod Kruger
2. 1890s: De Klerks Coppersmith
3. 1890s: Old house in Goldman Street, Florida - via Rod Kruger