He became a well-known writer, with novels such as A Selva (The Jungle), his best-known, Emigrantes (Emigrants), Eternidade (Eternity), and Terra Fria (Cold Land), which won the Ricardo Malheiros Prize [pt], in 1934, He also wrote several travel books.

[1][2] In 1973 Ferreira de Castro devoted a large part of his intellectual estate to the city of Sintra.

[3] I love that town deeply, for the immense poetry of Sintra's nature, where I meditated and dreamed so much, for its people who are such friends of mine, I did so because it was in Sintra that I wrote, for about thirty years, most of the work I produced in that long period, the most fruitful of my life.He died in 1974 shortly after the Carnation Revolution of 25 April 1974, which overthrew the Estado Novo.

The Ferreira de Castro Museum is situated to the immediate west of the centre of Sintra, a UNESCO World Heritage Site.

[2][4][5] Ferreira de Castro's collection consists of over 20,000 documents, including letters, periodicals, manuscripts, and photographs.