The 45,000 sq m proposal ( pictured) was pipped to the post by designs from Switzerland's Burckhardt + Partner and Bramberger and Atelier Thomas Pucher of Austria, who were jointly awarded first prize.
The international contest attracted more than 80 entries from 32 nations. However Mangera Yvars - one of the AJ's 40 Under 40 starlets - was the only British practice to make it onto the final shortlist.
Designed together with Arup's Advanced Geometry Unit, Mangera Yvars' scheme for the Islamic equivalent of the UN was envisaged as a series of dunes and pathways.
According to the design statement: 'The project [was] seen not as a building but rather as a new Islamic landscape.
'The scheme explores common themes in Islamic architecture, such as the use of structural geometric patterns, courtyards and the use of water as a unifying element.'
The building, which was to be sited on the axis with Mecca Gate and Jeddah city, was to be split into three sections, with the administration and secretariat units housed in a tower overlooking the conference and common areas.