Every aspect of the Barcelona Pavilion has architectural significance that can be seen at the advent of modern architecture in the 20th Century; however, one of the most important aspects of the pavilion is the roof. The low profile of the roof appears in elevation as a floating plane above the interior volume. The appearance of floating gives the volume a sense of weightlessness that fluctuates between enclosure and canopy. The roof structure is supported by eight slender cruciform columns that allow the roof to as effortlessly floating above the volume while freeing up the interior to allow for an open plan. With the low roof projecting out over the exterior and the openness of the pavilion, there is a blurred spatial demarcation where ht interior becomes and exterior and exterior becomes interior.