This building has a 10-floor structure, a basement floor and a covered parking lot; in it are 428 offices of the Congressional Representatives.
It is connected to Annex II through a tunnel where six belt conveyors and two staircases make circulation quicker and easier.
On the tenth floor of this annex there is a restaurant with a panoramic view of the Three Powers Square.
In the entrance of the restaurant, an indoor garden allows the free circulation of birds.
The external space shelters the simplicity of a small chapel designed by Oscar Niemeyer, where there is another work of the artist Marianne Peretti: a cross-shaped stained glass window.