Letter to Richard F. Fuller
p181“I live myself in the apartment described in Andersen's "Improvisatore" which get you and read as scene of the childhood of Antonio.”
Fuller, Margaret. The Letters of Margaret Fuller. Edited by Robert N. Hudspeth. Vol. V. Ithaca: Cornell University Press, 1988.
Fuller explicitly names "Andersen's 'Improvisatore'" and is currently living in the apartment in Rome described in the novel as the scene of narrator Antonio's childhood; she identifies her own room with one described in the novel and identifies it with a young painter (Hudspeth's notes clarify it is Federigo, a painter rather than a sculptor).