It is fascinating to read that someone's forebears lived on such
a famous address [050718 MMDigest].  However, it is not at all sure
that the house in which they lived was the same as where Gavioli
(and, before him, Corvi) had their workshop.

Many new roads and boulevards were built in that part of Paris between
1850 and 1880, including the rue de Citeaux (1861).  In 1868 the part
of the rue d'Aligre between place d'Aligre and Fauburg St. Antoine was
added to the original street, and in these cases often renumbering took
place.  The Gavioli factory had moved to the Av. Tailleburg since
about 1870.

I am preparing an article about Gavioli for the Dutch magazine and that
of the COAA in the US; then I may be able to add more clarity.

Greetings from the Netherlands,
Hans van Oost, webmaster of the KDV
http://www.draaiorgel.org/  (trilingual)