11_diagonal_street | floorcount | 20 <tsp> 11_diagonal_street | owner | redefine_properties_limited <tsp> 11_diagonal_street | architect | helmut_jahn <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 
11 diagonal street (which had 20 floors) was designed by architect helmut jahn and is owned by redefine properties limited.the building's architect was helmut jahn