The sports centre in Luxembourg-Belair, consistis of a 31m x 31m swimming pool and a 3-fold gymnasium with the dimensions of 36m x 46m. All these functions are connected by a solid plinth construction integrated in the slope. The transparent building of the hall has been designed as directional steel structure made of slim hollow box girders, which are welded and constructed according to static requirements. The square swimming pool is covered by a non-directional girder grid construction made of glued-laminated timber. Whereupon, the materials were selected considering the very high requirements to prevent corrosion. The invisible joint of the slim girders (24 x 200 cm) have been realized by using slotted plate/ drift pin points. F30 can easily be achieved due to the all-round timber covering. Both halls are covered by prefabricated roof panels which are nailed to a rigid brace slab.