The 10, 488-square-metre office block was designed by São Paulo studio Mira Arquitetos for the independent organisation, which represents local municipalities to Brazil's federal government and the national congress.
The building is located on a site containing a cluster of governmental departments, close to the Esplanada dos Ministérios, an area at the end of the Eixo Monumental in the city.
The National Confederation of Municipalities is intended to slot into its urban context and is incorporated within an area of landscaping.
A monolithic concrete basement containing two levels of car parking extends above ground to form a perimeter that encloses a paved courtyard.
This communal courtyard is flanked by a large auditorium on one side and a series of smaller rooms on the other, with glazed walls providing a visual connection between indoors and outdoors.
"The design of the ground floor was the guiding principle of the proposal," said the architects. "We have created a square, slightly sunken in relation to the mid-level of the terrain, which unfolds on two levels and results in a new topography for the lot."
The ground floor spaces also include a restaurant and a foyer situated within a multi-storey void. This void also incorporates circulation that leads to the office areas on the levels above.
A bridge that traverses the foyer space provides a dedicated access route to the offices. An external staircase extending between this upper level and the courtyard ensures visitors can access the auditorium from the courtyard without affecting the office workers.
"The ground floor has two purposes," said the architects, "it is both support for the settlement of the new set and an interface with the city."
The double-height block containing the auditorium supports a further perpendicular volume that features glazed facades shielded behind a horizontal metal grille.
This elongated glass box contains the main administrative spaces, which receive plenty of natural light and look out across the surrounding neighbourhood.
Large concrete columns support a section of the office volume that cantilevers over a shallow pool on the roof of one of the ground-floor blocks. At the other end, the horizontal box extends over another narrower pool above the restaurant.
Photography is by Leonardo Finotti and Haruo Mikami.
Architects: Mira arquitetos (Luís Eduardo Loiola and Maria Cristina Motta)
Collaborators: Ana Carolina Sumares, Luís Felipe da Conceição, Marcelo Ribas, Luisa Leme Simoni, Gabriela Lira Dalsecco
Structure: Kurkdjian e Fruchtengarten Engenheiros Associados , Mag Solos Engenheiros Associados
MEP: MHA Engenharia
Lighting: Lux projetos
Landscape design: Gabriela Ornaghi
Constructor: Soltec Engenharia