Attributed to Bernardino Licinio - Portrait of an architect with a self-portrait in a mirror (c.1530s)
Oil on panel, ~ 60x80 cm
Recent studies revealed that it's not just 'an architect', but likely Sebastiano Serlio, indeed an Italian architect who lived in Venice from around 1527-28 until 1540-41 (then he moved to France, invited by Francis I himself).
And Bernardino Licinio was born and worked in Venice, too - which is kind of important for this story. Venice in general played a large role in the history of art, but we also know about one very specific pivot point in the history of mirrors that happened there.
In 1507, the brothers Andrea and Domenico d'Angelo dal Gallo received a 20-year privilege from the Venetian Council of Ten for their perfected method of making flat glass mirrors from cristallo glass. Venice would dominate the mirror business for roughly the next century and a half.
This remarkable transition from convex to flat mirrors was astonishingly well captured by two of the greatest Venetian artists of the era - the old Bellini and the young Titian. Both depicted scenes in which two different types of mirror are juxtaposed (both paintings are c. 1515s):
Notice how small these first flat mirrors were - the limitations of making flat sheets from blown glass didn't allow mirror-makers to produce very large ones.
So the mirror in the Licinio painting looks problematic. Judging from the size of the painting, it seems to be roughly 40-50 cm across - enormously large for an apparently flat glass mirror of around 1530. Not completely impossible, perhaps, but very, very doubtful.
Also, the frame looks suspiciously modern in its simplicity. We have an example of an early-16th-century mirror frame from Venice, currently in the collection of the MET, which looks almost architectural compared with the minimalist design in the Licinio:
Despite its monumental appearance, its actual mirror opening was only about 23 × 25 cm, smaller than your A4 sheet. Yet it was seen as HUGE by the contemporaries.
There are actually alternative attributions of this 'self-portrait' - for example, one of the scholars attributed the painting to Giovanni Battista Paggi, another Italian painter, and dated it to around 1580s
For me the current attribution to Licinio is still more credible, but perhaps we need to rethink the meaning of the composition. If we take into account the technological context, it leans more towards an 'imagined mirror' than a literal self-portrait in an actual mirror.
Sebastiano Serlio was actually known less for his buildings than for his very influential treatise on architecture - where he described not only what architecture was, but what it should be. Perhaps this mirror works in a similar way: a kind of roadmap for how mirrors were imagined when the actual mirrors were not quite there yet.
The painting is now in the collection of the little-known Martin von Wagner Museum of the University of Würzburg, Germany. This is how it looks in its seemingly original frame: