CAIXA Cultural Brasília is one of the more reliable places in the capital to find a temporary exhibition, small theatre performance, film series, or concert. It sits in the banking sector, close enough to the Eixo Monumental to combine with the big Niemeyer landmarks, but its programme is more varied and less monumental than the architecture around it.
The appeal depends on what is showing, so check the current listings rather than treating it as a fixed museum collection. When the programme is strong, it is a good way to see Brasília as a working cultural city rather than only as a planned-capital set piece. It is also useful in the heat or rain, when an indoor stop near the central axis is welcome.