He studied at the National School of Decorative Arts in Paris and moved to Brazil in 1894. There he worked on different projects, such as the General Carneiro station in Belo Horizonte and was a professor at the School of Fine Arts in Curitiba.
Career
He arrived in Buenos Aires on 1 November 1896, there he developed most of its projects and concrete works. One of his first works there is the bakery La Burdalesa (Paraná nº 861/9, year 1898, already demolished). In 1901 he revalidated his diploma in the University of Buenos Aires and entered the Central Society of Architects (SCA). In 1902 he finished the Artistic Ironworks Motteau, with remarkable art nouveau style (Avenida Juan de Garay no. 1272, demolished) and later the headquarters of the society of mutual savings La Bola de Nievein Buenos Aires and in Rosario, province of Santa Fe (Cordoba and Laprida streets, year 1906).
He obtained the Municipal Prize for the Best Facade of 1903 for the residence he built for Bartolomé Ginocchio in Lima Street No. 1642. Two years later he received the third prize for the façade of Felix Egusquiza's residence on Libertad Street No. 1394 and in 1907 presided over the SCA. Thanks to these recognitions, different aristocratic families hire him to make his large residences in the Barrio Norte. The most important of these is the Fernández Anchorena Palace, now home to the Apostolic Nunciature, on Avenida Alvear 1637, built between 1907 and 1909. Another house, smaller but also lavish, was built on Avenida de los Incas 3260, where it is still standing.
In the second half of the 1920s, and until the crisis of 1929, there was a great rise of financial institutions in Argentina. All of them built large parent companies in downtown Buenos Aires, which ended up taking the role of financial city that conserves today. Le Monnier was in charge of the headquarters of the Uruguayan Argentine Bank (Avenida Roque Sáenz Peña nº 501, year 1928) and the neighboring buildings of the Bencich brothers, owners of a construction company (Edificio Bencich, Av. Roque Sáenz Peña 615 and Edificio Miguel Bencich , Av. Roque Sáenz Peña nº 614/6).