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 
the 20-floor 11 diagonal street designed by architect helmut jahn is owned by redefine properties limited.the building's architect was helmut jahn