What characterizes the twin towers of the National Congress?

The twin towers of the National Congress, located in Brasília, Brazil, are notable for their unique architectural design. They indeed appear cubic at first glance, which can lead to the assumption that they are solid geometric forms. However, in actuality, their structure is five-sided, providing a complex visual that challenges traditional perceptions of cube-like forms. This five-sided design allows for an interesting interplay of light and shadow, as well as varied perspectives from different viewpoints around the towers.

In contrast, the other options do not apply accurately to the National Congress towers. Describing them as solidly cubic would overlook the intricacies of their design. As for residential use, the twin towers serve a civic function, housing the legislative branch of government rather than being intended for residential purposes. Although the towers might share some characteristics with Brutalist architecture, emphasizing raw materials and functionality, their specific design does not strictly adhere to that philosophy, which more commonly features heavier, coarse materials and a focus on mass and form. Thus, the correct characterization of these towers is their five-sided appearance, which distinguishes them in architectural discussions.