The buildings Oscar Niemeyer and Roberto Burle Marx laid out for the city's 400th anniversary in 1954: the Oca, a plain white dome used for large exhibitions, linked to the Biennial pavilion and the auditorium by a long free-form marquee that is the piece architects come for. The Museum of Modern Art and the Afro Brasil museum sit in the same group. The park around them is already on this site; these are the reason to look up while you are in it.