11_diagonal_street | completiondate | 1983 <tsp> 11_diagonal_street | floorcount | 20 <tsp> 11_diagonal_street | architect | helmut_jahn <tsp> 11_diagonal_street | floorarea | 1200 (square metres) <sep> 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 buildingthe building's architect was helmut jahn 
the architect of 11 diagonal street is helmut jahn and it was completed in 1983. it has 20 floors and a floor area of 1200 square metres.the building's architect was helmut jahn