The Convention Centre, built to designs by J.J.P. Oud, was completed by his son in 1968. It is an enormous complex with walls surfaced in yellow bricks and sky-blue tiles, topped with a 17 storey triangular tower. On the north side, the red and blue mosaic adorning the wall of the entrance is by Karel Appel. The Convention hall (sometimes used to stage shows) fills three floors and has 2000 seats. Under ground there is another hall in which banquets and exhibitions are held.