BARCELONA.- As of December 10 the Mies van der Rohe Pavilion will be the object of an intervention that reflects on the use of buildings and our concept of them as unique, unalterable spaces. The artist Ai Weiwei, one of the leading and most controversial figures of Chinese contemporary art, will fill the Pavilion pools with two elements that, though very common in our everyday lives, are totally foreign to architectural construction. He will replace the water of the two pools, one exterior and the other interior, with milk and coffee, respectively. In the words of the artist himself