In order to achieve a logical system on the ground floor Groosman and Partners used a urban design like grid painted on the floor. Because of the enormous height a large part of the inner volume of the halls remained unused. Groosman Partners Architecten launched the idea to add a second grid system on the level of 8 meters high, to double the usable surface of the halls. Several ways of use can be implemented within this technical framework and change of use can be easily realised. The plug-in system is extendable as well as dismountable. The floor underneath the added structure is used for production as well as events. Referring to the concept of a city inside a hall, a large photograph of a detailed satellite image of the port of Rotterdam was placed on the underside of the office.