| 11 Diagonal Street | |
| Location: | Johannesburg, South Africa |
| Coordinates: | -26.2042°N 28.0358°W |
| Status: | Complete |
| Start Date: | 1981 |
| Completion Date: | 1983 |
| Opening: | 1984 |
| Building Type: | Multi use, Office |
| Antenna Spire: | 80m (260feet) |
| Roof: | 75m (246feet) |
| Top Floor: | 75m (246feet) |
| Floor Count: | 20 |
| Elevator Count: | 6 |
| Cost: | R65 million |
| Floor Area: | 20000m2 |
| Architect: | Helmut Jahn |
| Owner: | Rebosis Property Fund |
11 Diagonal Street is an office tower in Johannesburg, South Africa. It was built in 1983 to a height of 80 metres. It is designed to look like a diamond as it reflects different views of the Central Business District from each angle of the building.[1]
The building's architect was Helmut Jahn.
The building is currently used by the department of Development Planning & Local Government.[2]