It's not an illusion - See this Mandela statue

Steel Column Installation Honouring Nelson Mandela by Marco Cianfanelli.

This incredible structure was installed in Howick, South Africa, to commemorate 50 years since Nelson Mandela was arrested and charged with treason in the same place.

It consists of 50 steel columns that look randomly placed – but when you look at them at the right angle, they show a clear image of Mandela's face.

Source: google.com/photos