The Villa Valsovano, where the English writer Percy Bysshe Shelley stayed in the summer of 1819, is not easy to find since it is listed in many places as being in Via del Fagiano which is where the original entrance to the villa was.
However, to see the villa these days you have to go to Via Filippo Venuti, near Livorno's hospital, about 20 minutes' walk from the city centre.
Villa Valsovano stands in a narrow side street off Via Venuti, at number 23. It is not marked on the main street so is very easy to miss unless you know what you are looking for. There is a kind of storage yard on the corner. These photos show what to look for.
How to get there: Bus no. 8R from Via Cogorano (near Piazza Grande)
To see the location of the Villa Valsovano on a map, click here
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This is not the Villa where Shelley and Mary lived. The house at Via Filippo Venuti 23, Livorno, with a plaque recording the Shelleys’ residence June-September 1819, is not near Montenero, where the Shelleys were; and the Villa Valsovano as photographed by William Hall Griffin (d. 1907) in the 1890s (see The Letters of Percy Bysshe Shelley, ed. Roger Ingpen, 2 Vols., 1909, ii. facing 694) is a different building completely.
What you say is very interesting. However, the building is clearly marked on a map from 1836 (Livorno con la nuova cinta, ASF). Since then it has been drastically modified, hence its current appearance which bears little resemblance to the villa at the time of Shelley's stay.