This paper aims to comment on the essay En la Habana from César Aira (2016) in relation to the idea of notation by Barthes. In this short text, Aira narrates a walk in the Cuban city, starting at the house of Lezama Lima and continuing through other places —especially museums— where he finds certain objects that draw his attention and lead him to take extensive notes about them. The essay turns out to be some sort of travel journal, where Aira’s thoughts on the writing of what is seen and its later use in literary creation come across. In this regard, the essay could relate to the practice of notation described by Barthes in The preparation of the novel (1978-1980), an idea that had already been explored in some of the most classic essays of the critic, particularly in “Introduction to the structural analysis of narratives” (1966) and “The reality effect” (1968). Between the taking of notes of Aira and the Barthesian practice of notation, we can observe an old but insistent problem of literature: the writing of the “Real”.