Montreal Building, Residential building in the República district, São Paulo, Brazil

The Montreal Building is a 24-storey residential tower at the junction of Avenida Ipiranga and Avenida Cásper Líbero, opposite Praça Alfredo Lessa. Its 21 floors hold 230 studio apartments of 36 to 48 square metres, many with trapezoidal plans. The north facade carries horizontal aluminium fins, while the Cásper Líbero side has cadmium-yellow blades; the entrance hall in the first basement holds three mosaic panels by Di Cavalcanti.

Designed by Oscar Niemeyer in 1950 and built from 1951 under Carlos Lemos, the Montreal Building opened in 1954, timed to São Paulo's fourth centenary. It was the first of Niemeyer's large-scale works in the city, predating the Copan, Triângulo and Califórnia buildings, and was commissioned by the Banco Nacional Imobiliário to house single occupants and small families in the verticalizing centre.

The building's name comes from Avenida Ipiranga's junction with Avenida Cásper Líbero, formerly Rua Conceição, in São Paulo's centre. In the ground-floor hall, three large mosaic panels by Emiliano Di Cavalcanti greet residents. The north façade's horizontal fins echo Niemeyer's Banco do Estado de Minas Gerais from the same period.

The building occupies a narrow, irregular corner where Avenida Ipiranga meets Avenida Cásper Líbero, opposite Praça Alfredo Lessa. The entrance hall with Di Cavalcanti's mosaics is on the first basement level, so visitors should look for the stair or ramp down rather than a street-level lobby. The brise-soleil on both avenue façades was removed in a 2004 renovation.

The Montreal Building was the first of Niemeyer's large-scale works in São Paulo, predating the Copan, Triângulo and Califórnia buildings. Its north façade's horizontal fins closely resemble those of the Banco do Estado de Minas Gerais, designed by Niemeyer in the same period.