The design was conceived as a response to what seemed like a battle to be lost.
The European Central Bank was going to build a skyscraper on the scene of the crime - next to The Grossmarkthalle. The two building creating a X and a Y axises in a gigantic Cartesian coordinate system. One embodying the history, the other one the future. The horisontal; Grossmarkthalle (a historic landmark), pointing backwards, and the vertical; the ECB-highrise pointing upwards - towards the future.
They were going to build a giant monuments in glass and steel, to celebrate money and progress on the site of Nazi violence and hate. The designteam realised that a new structure build in the memory of Frankfurt jews couldn't possibly win the battle for attention with this giant - it would be like raising a tombstone - a ridiculously small one, that would give the impression that we were trying to bury the memory of holocaust.
Building nothing was the only possible option...to do the absent monument.