The Office for Metropolitan Architecture, (OMA), is the Rotterdam based architecture firm of Dutch architect Rem Koolhaas. The firm was founded in 1975 by Rem Koolhaas and Elia Zenghelis with Madelon Vriesendorp and Zoe Zenghelis. The Office for Metropolitan Architecture (OMA) is a leading international partnership practicing contemporary architecture, urbanism, and cultural analysis. The office is currently led by six partners – Rem Koolhaas, Ole Scheeren, Ellen van Loon, Reinier de Graaf, Shohei Shigematsu and Managing Partner, Victor van der Chijs – and employs a staff of around 220 of 35 nationalities. Architects, researchers, designers, model makers, industrial designers and graphic designers work in close collaboration, and expert consultants are intimately involved from the beginning of the design process.